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Tuesday, 7 February 2017

A Coaches' Guide to Strength Development Part X: Eccentric Training Part II - Practical Application & Periodization Implications; a guest-post from Dr Angus Ross

photo courtesy justynwarner.com 


As discussed in Part I, eccentric (ECC) training has had a relatively comprehensive scientific backing behind it already and from what I have seen in social media in the sport science world, it is currently the subject of numerous studies and ongoing PhDs around the globe. Questions remain in terms of how to best apply ECC training in the field, but several authors/coaches/trainers have used/prescribed it extensively and in particular, I note that Dietz & Peterson’s Triphasic Training book has several chapters detailing their use and prescription/periodization of ECC loading (in conjunction with both isometric and iso-inertial options). 

My philosophies are influenced from a range of these sources, as well as from my own trial and error and hopefully at this point they do have some logical basis behind them. No doubt these philosophies will continue to evolve as we learn more, and I am in the happy position of co-supervising two talented PhD students working in this area currently - so look out for further work from Jamie Douglas and Farhan Tinwala in the years to come.

The rules of adaptation to ECC training are certainly not hard and fast, and will vary between individuals - dependent on their genotype, performance needs and training background. However I do try to use - or at least consider - the following principles or observations in prescription, which I think are at least somewhat grounded in science (most of which have been touched on in the previous post).

  • Slow ECC phases without additional load (not beyond the concentric load) advocated by many practitioners certainly increases time under tension, perhaps helps groove a motor pattern - so it seems like a good introductory option for ECC work to set up skills, postures, develop hypertrophy and provide a protective effect against increasing DOMS in subsequent phases
  • Slow high tension (overloaded beyond concentric) ECC and isometric work – are likely to develop tissue integrity, including increases in both muscle CSA & tendon stiffness – potential changes in overall stiffness potential likely occur from this. Note that this type of training will induce additional DOMS in initial sessions.
  • SSC and/or neural-motor control-driven performance benefits may be realized relatively quickly following ECC training. Anecdotal and experimental evidence with both high performance athletes and moderately conditioned subjects suggest that these gains likely will be maintained for several weeks after the conclusion of ECC training. 
  • ECC training has greater cortical activation but decreased muscle activation relative to CON work – resulting in decreased peripheral fatigue for a given load, and a lower metabolic cost. Perhaps implications from this in terms of the training load that can be tolerated - i.e. a greater volume of work - can be tolerated at a muscle level as compared to other training modalities. A potential drawback (and not one with any real scientific evidence to date) is the possibility of central fatigue resulting from the ECC loading as a result of the high cortical drive combined with high volume and/or the peripheral damage and subsequent inhibition. An interesting question is whether this relates to the delay in realization of some performance adaptations post ECC training?  
  • As alluded to in Part I of the ECC series (and in the point above), evidence suggests that gains in concentric-only performance metrics (e.g. concentric muscle power) may take longer to occur, or at least be maximised after the cessation of an ECC training intervention. Subsequently, the administration of eccentric training should be planned carefully with regard to the phasing of performance peaks relative to competition schedules. Additionally on-going monitoring of the patterns of adaptation of the individual athletes needs to be considered to optimize competition performance.
  • To facilitate rapid transfer of positive adaptations from ECC training to performance it makes sense to include specific skill work and some dynamic concentric or SSC loading throughout any ECC dominated training phases.
  • Eccentric work is pretty taxing and I rarely go more than 3 weeks on the trot without a substantial change, indeed 2 weeks on 1 off (and then returning back to the ECC loading in week 4) may be a better loading routine if a longer ECC phase is required.
  • Fast ECC work may increase the relative proportion of FT muscle and optimize dynamic power performance. It should be noted however that modalities that induce true fast ECC work (i.e. joint angular velocities in excess of 180o -1 ) with high tensions throughout the movement range are most likely to be motor-driven or have an external power source. Many non-motorized versions of fast ECC work end up being variations of largely switching off the targeted muscle and dropping rapidly and then trying to turn the muscle on rapidly at end of range -  these are arguably not the same stimulus as what has been used in the literature when significant shifts to FT muscle have been observed; though potentially some of these ‘down and dirty’ gravity driven approaches may have some effect, and likely do help with performance in SSC and stiffness.
  • A background of ECC training appears to maintain strength qualities and muscle cross-sectional area longer during detraining than might be seen with concentric only or traditional training (Coratella & Schena, 2016). Again implications here for detraining and tapering.

photo courtesy justynwarner.com

Proposed Periodization

My intention with a proposed periodization of ECC training for a power athlete is based on some understanding of what the adaptations we are trying to achieve are, and an understanding of where an athlete is at in terms of development. Obviously this will effect the relative emphasis of any phase to suit individual need. A final point to consider is the individual response to the loading and I completely agree with Stu’s point in Part V of this series that periodization of the output is critical (rather than just the input). So with that in mind, tracking of adaptation (or perhaps current organism state) needs to occur throughout the process to make sure we never get too far away from our ultimate objective of getting better at the sport. That is, it is counterproductive to get to the point where ECC training may have rendered the actual event or sport training to be too far away from optimal for it to be worthwhile. These factors considered, my current thought processes (subject to change as we learn more!) and typical phases in chronological order are as follows;
  • Train to train – initial training block post time off - e.g. after a pinnacle event, training moderate to high rep range with standard iso-inertial training - i.e. typical barbell work with both concentric and eccentric phases in the 5-12 rep range.  Objective: re-introduction to training and DOMS-protection for blocks to come.

  • Slow ECC phase – tempo based, but ECC load the same as CON load, typically in this phase I would include slow eccentric work in key (or sport relevant) exercises, as well as some on normal CON-ECC iso-inertial work - at least in warm up sets. Option to also include some isometric holds in key positions in this phase. Objective: hypertrophy of muscle and tendon and motor control (spinal stacking), & again DOMS protection for upcoming blocks.

  • Overloaded ECC work – slightly faster ECC tempo but with an overloaded ECC phase. Options for adding in dynamic concentric work here and certainly with this sort of training I would be advocating 2 weeks on, then 1 off to ensure sport specific skills can be maintained at  a suitable intensity during the week off the ECC overload stress. Objectives: ongoing fast twitch hypertrophy (sarcomeres in series?), plus stiffness and eccentric strength development

  • Fast ECC work – If the modalities are available, this should include eccentrically overloaded movements at fast angular joint velocities (in excess of 180os-1) throughout the range of motion. With gravity-based loading options in this phase you can include rapid RFD by sticking isometrically at end of fast movement through the ECC range, we have also used bands during this phase to facilitate the fast ECC loading. Options for adding in dynamic concentric work here also. Objective:  increased expression of fast muscle contractile protein plus strength/rigidity in amortization phase + further tendon adaptations

  • Ballistic training – fast down and fast up – reactive focus with lighter loads typically (can be done with or without an overloaded ECC phase). Objectives: dynamic amortization phase and explosive force production

  • Competition taper or Competition phase – very low volume of strength training in general, may include periodic low volume maintenance of loaded fast ECC qualities (e.g. 1-2 sets every couple of weeks) and/or isotonic power/strength. Length of this phase will vary between athletes depending on training age, their strength reserve, their muscle size reserve, and obviously how they respond to reduced load. Noting again that this period may be longer than expected with athletes that now have an eccentric training background.  Objectives: promote overshoot of FT muscle (see Andersen & Aagaard 2000), maintain strength and CSA (or minimize loss), maintain fascicle length (or minimize loss), allow un-inhibited expression of CON power as well as ECC and SSC performance

photo courtesy justynwarner.com

With such a periodization, I would be seeking or expecting the performance adaptations as detailed in Figure 1 below. That is I would expect max force capabilities (which by definition are delivered at low velocities) will adapt positively to the initial phases of the training. In contrast, the high speed power (with greater sport performance implications) may be negatively affected by the same training interventions. In the latter phases, a reduction of volume, less max force work, and a higher speed emphasis in training (including the fast ECC) should set up the environment for recovery from DOMS and inhibition, and potentially for the proliferation of fast contractile proteins in muscle. The expectation from this would be that convincing gains in high speed power are elicited, with this quality peaking right at the end of the periodization. Notably there could well be mild decrements in the max force abilities of the athlete during the later stages with the concomitant gains in high speed power; the trick being to ensure the blue line below always remains above a ‘strong enough’ threshold (noting that this may actually be lower than you think in some disciplines) during a competition phase to maintain sport performance.



Putting it in practice - Eccentric Exercise Options 

Eccentric exercises need to be simple to perform and safe to terminate when an athlete’s technique is compromised.  It is possible to create supra-maximal eccentric loads even without access to specific eccentric loading machinery by being creative with variations of conventional exercise.  However, as has been mentioned previously on occasions, an ECC motor-driven option does offer real advantages.  The below is by no means an exhaustive list but gives some example modalities or options with emphasis on those that can be done without excessive extraordinary equipment options:


High Tension ECC exercises (load > CON load)
  • Perform ‘2-up 1-down’ exercises – for example, lift concentrically with 2 limbs and lower with 1 during a leg press or hamstring curl, calf raise etc. 
  • Combine CON and ECC exercises – for example, combine a push up with a Nordic hamstring lower, or a hang clean to an ECC bicep curl.
  • Partner applies load (i.e. pushing/pulling down) during the ECC phase e.g. during a squat, hip thrusts, bench press, or pull up (see Figure 2).
  • Motor-assisted CON phases to allow ECC overload


Figure 1: Eccentric partner-overloaded Hip Thrusts


Fast ECC options (aiming for joint velocities ≥180os-1)
This type of eccentric training is harder to achieve with any control without expensive motor driven equipment options, with that in mind I have included both the gold-standard motor driven devices, as well as some perhaps more accessible options.
  • Fast motor driven devices e.g. recumbent ECC bike, passive leg press, isokinetic devices. Notably I have yet to have access to these devices on a regular basis, so I don’t see them as a necessity but certainly would be in the ‘nice to have’ category.
  • Absorbing energy rapidly – for example, landing from a box (bodyweight or added load - Figure 3), acceleration to rapid deceleration run, or a downhill sprint with additional load, running\jumping downstairs with additional load (weighted vest), partner push down kettlebell swings, (noting that all of these exercise are arguably not strictly fast ECC except for a very small range – better make sure that ROM is specific to the sport!). Banded resistance work is also useful in creating the acceleration in the ECC phase. 
  • Accentuated eccentric phase via added load released prior to concentric phase – for example weight releasers for barbell exercises such as squat, bench press, push press (see Figure 4) or dropping DBs on the ECC/CON turnaround of a vertical jump (arguably same issues as point above).

Figure 2: Box Drop with additional load


Figure 3: Weight release push press


Overall Summary & Suggestions 

In summary, eccentric training should be considered by/for athletes with appropriate strength training experience where:
  • There is sufficient time in the training organization for potential long-terms gains from eccentric training intervention that outweigh potential short-term losses
  • The fast contractile properties of muscle are critical to performance outcomes and-or
  • Gains in strength, leg spring stiffness and-or hypertrophy are needed and-or
  • Strong stretch-shortening-cycle contributions is critical to performance – optimizing RFD and elastic return

Finally, periodization of the eccentric work should include the introduction of the eccentric work well before the competition season to allow assessment of both its acute and chronic performance effects on the athletes in question. Periodization options may include periodic low volume ‘top up’ of ECC qualities during the competition taper.


References 

Andersen, J.L., Aagaard, P. (2000) Myosin heavy chain IIX overshoot in human skeletal muscle. Muscle & Nerve, 23:1095-1104
Albracht, K., Arampatzis, A., (2013) Exercise-induced changes in triceps-surae tendon stiffness and muscle strength affect running economy in humans. European Journal of Applied Physiology, 113: 1605-1615
Asklling, C., Kar;sson, J., Thorstensson, A. (2003) Hamstring injury occurrence in elite soccer players after preseason strength training with eccentric overload. Scandinavian Journal of Medicine and Science in Sports, 13: 244-250
Blazevich, A.J., Cannavan, D., Horne, S., Coleman, D.R., Aagaard, P. (2009) Changes in muscle force-length properties affect the early rise of force in vivo. Muscle & Nerve, 39: 512-520
Butterfield, T.A., Leonard. T.R., Herzog, W. (2005) Differential serial sarcomere number adaptations in knee extensor muscle of rats is contraction type dependent. Journal of Applied Physiology, 99: 1352-1358
Cermak, N.M., Snijders, T., McKay, B.R., Parise, G., Verdijk, L.B., Tarnopolsky, M.A., Gibala, M.J., Van Loon, L.J.C. (2013) Eccentric exercise increases satellite cell content in type II muscle fibres. Medicine and Science in Sports and Exercise, 45(2): 230-237
Colliander, E.B., Tesch, P.A. (1992) Effects of detraining on eccentric and concentric muscle strength. Acta Physiologica Scandinavica, 144: 23-29
Cook, C.J., Beaven, C.M., Kilduff, L.P. (2013) Three weeks of eccentric training combined with overspeed exercise enhances power and running speed performance gains in trained athletes. Journal of Strength and Conditioning Research, 27(5): 1280-1286
Coratella, G., Schena, F. (2016) Eccentric resistance training increases and retains maximal strength, muscle endurance and hypertrophy in trained men. Applied Physiology Nutrition and metabolism, 41 (11): 1184-1189
Douglas, J., Pearson, S., Ross, A., McGuigan, M. (2016a) Chronic adaptations to eccentric exercise: A systematic review. Journal of Strength and Conditioning Research, (Epub ahead of print)
Douglas, J., Pearson, S., Ross, A., McGuigan, M. (2016b) Eccentric Exercise: Physiological characteristics and acute responses. Sports Medicine (Epub ahead of print)
Elmer, S., Hahn, S., McAllister, P., Leong, C., Martin, J. (2012) Improvements in multi joint leg function following chronic eccentric exercise. Scandinavian Journal of Medicine and Science in Sport, 22(5): 653-661
Fang, Y., Siemionow, V.,  Sahgal, V., Xiong, F., Yue, G.H. (2001) Greater movement-related cortical potential during human eccentric vs concentric muscle contractions. Journal of Neurophysiology, 86(4): 1764-1772
Farthing, J.P., Chilibeck, P.D. (2003). The effect of eccentric and concentric training at different velocities on muscle hypertrophy. European Journal of Applied Physiology, 89: 578-586
Franchi, M.V., Atherton, P.J., Reeves N.D., Fluck, M., Williams, J., Mitchell, W.K., Selby, A., Beltran-Valls, R.M., Narici, M.V. (2014) Architectural, functional, and molecular responses to concentric and eccentric loading in human skeletal muscle. Acta Physiologica (Epub ahead of print)
Fridén, J. (1984) Changes in human skeletal muscle induced by long-term eccentric exercise. Cell tissue research, 236(2): 365-372
Gibson, W., Arendt-Nielsen, L., Taguchi, T., Mizumura, K., Graven-Nielsen, T. (2009) Increased pain from muscle fascia following eccentric exercise: animal and human findings. Experimental Brain Research, 194: 299-308
Gross, M., Luthy, F., Kroell, J., Muller, E., Hoppeler, H., Vogt, M. (2010) Effects of eccentric cycle ergometry in alpine skiers. International Journal of Sports Medicine, 31: 572-576
Harridge, S.D.R. (2007) Plasticity of human skeletal muscle: gene expression to in vivo function. Experimental Physiology, 92(5): 783-797
Heinemeier, K.M., Olesen, J.L.,  Haddad, F.,  Langberg, H.,  Kjaer, M.,  Baldwin, K.M. and Schjerling, P. (2007) Expression of collagen and related growth factors in rat tendon and skeletal muscle in response to specific contraction types. Journal of Physiology 582(3): 1303-1316

Higbie, E.J., Cureton, K.J., Warren, G.L., Prior, B.M. (1996) Effects of concentric and eccentric training on muscle strength, cross-sectional area and neural activation. Journal of Applied Physiology, 81: 2173-2181
Hortobagyi, T., Hill, J.P., Houmard, J.A., Fraser, D.D., Lambert, N.J., Israel, R.G. (1996) Adaptive response to muscle lengthening and shortening in humans. Journal of Applied Physiology, 80(3): 765-772
Karamanidis, K., Albracht, K., Braustein, B., Catala, M.M., Goldmann, J.P., Bruggemann, G.P. (2011) Lower leg musculoskeletal geometry and sprint performance. Gait & Posture, 34: 138-141
Kumagai, K., Abe, T., Brechue, W.F., Ryushi, T., Takano, S., Mizuno, M. (2000) Sprint performance is related to muscle fascicle length in male 100m sprinters. Journal of Applied Physiology, 88: 811-816
Lau, W.Y., Blazevich, A.J., Newton, M.J., Wu, S.S.X., Nosaka, K. (2015). Changes in electrical pain thresholds of fascia and muscle after initial and secondary bouts of elbow flexor eccentric exercise. European Journal of Applied Physiology, 115: 959-968
Leong, C.H., McDermott, W.J., Elmer, S.J., Martin, J.C. (2014) Chronic eccentric cycling improves quadriceps muscle strength and maximal cycling power. International Journal of Sports Medicine, 35: 559-565
Lindstedt, S.L., LaStayo, P.C., Reich, T.E., (2001) When active muscles lengthen: Properties and consequences of eccentric contractions. News Physiol Science, 16: 256-261
Linnamo, V., Bottas, R., Komi, P.V. (2000) Force and EMG power spectrum during and after eccentric and concentric fatigue. Journal of Electromyography and Kinesiology, 10 (5) 293-300
Liu, C., Chen, C-S., Ho, W-H., Fule, R.J., Chung, P-H., Shiang, T-Y. (2013) The effects of passive leg press training on jumping performance, speed and muscle power. Journal of Strength and Conditioning Research, 27(6): 1479-1486
Lynn, R., Morgan, D.L. (1994) Decline running produces more sarcomeres in vastus intermedius muscle fibres than does incline running. Journal of Applied Physiology, 77(3): 1439-1444
Mackey, A.L., Donnelly, A.E., Turpeeniemi-Hujanen, T., Roper, H.P. (2004) Skeletal muscle collagen content in humans after high force eccentric contractions. Journal of Applied Physiology, 97: 197-2003
Malliaras, P., Kamal, B., Nowell, A., Farley, T., Dhamu, H., Simpson, V., Morrissey, D., Langberg, H., Maffulli, N., Reeves, N.D. (2013) Patellar tendon adaptations in relation to load-intensity and contraction type. Journal of Biomechanics, 46: 1893-1899
Miyaguchi, K., Demura, S. (2008) Relationships between muscle power output using the stretch-shortening cycle and eccentric maximum strength. Journal of Strength and Conditioning Research, 22(6): 1735-1741
Paddon-Jones, D., Leveritt, M., Lonergan, A., Abernethy, P. (2001) Adaptation to chronic eccentric exercise in humans: the influence on contraction velocity. European Journal of Applied Physiology, 85: 466-471
Roig, M., O’Brien, K., Kirk, G., Murray, R., McKinnon, P., Shadgan, B., Reid, W.D. (2009) The effect of eccentric versus concentric resistance training on muscle strength and mass in healthy adults: a systematic review with meta-analysis. British Journal of Sports Medicine, 43: 556-568
Sacks, R.D., Roy, R.R. (1982) Architecture of the hind limb muscles of cats: Functional significance. Journal of Morphology, 173:185-196
Sayers, S.P., & Clarkson, P.M. (2001) Force recovery after eccentric exercise in males and females. European Journal of Applied Physiology, 84: 122-126
Schleip, R., Muller, D.G. (2013) Training principles for fascial connective tissue; scientific foundations and suggested practical applications. Journal of Bodywork and Movement Therapies, 17: 103-115
Seger, J.Y., Arvidsson, B., Thorstensson, A. (1998) Specific effects of eccentric and concentric training on muscle strength and morphology in humans. European Journal of Applied Physiology, 79: 49-57
Seynnes, O.R., de Boer, M., Narici, M.V. (2007) Early skeletal muscle hypertrophy and architectural changes in response to high-intensity resistance training. Journal of Applied Physiology, 102: 368-373
Sheppard, J., Hobson, S., Barker, M., Taylor, K., Chapman, D., McGuigan, M., Newton, R. (2008) The effect of training with accentuated eccentric load counter movement jumps on strength and power characteristics of high-performance volleyball players. International Journal of Sports Science & Coaching 3(3): 355-363
Tannerstedt, J., Apro, W., Bloomstrand, E. (2009) Maximal lengthening contractions influence different signalling responses in type I and type II fibres of human skeletal muscle. Journal of Applied Physiology, 106: 1412-1418
Tesch. P.A., Dudley, G.A., Duvoisin, M.R., Hather, B.M., Harris, R.T. (1990) Force and EMG signals during repeated bouts of concentric or eccentric muscle actions. Acta Physiologica Scandinavica, 138: 263-271
Timmins, R.G., Presland, J., Maniar, N., Shield, A.J., William, M.D., Opar, D.A. (2015) Architectural changes of biceps femoris after concentric or eccentric training. Medicine and Science in Sports and Exercise EPUB ahead of print
Tinwala, F., Haemmerle, E., Ross, A., Cronin, J. (2016) Eccentric strength training: a review of the available technology. Journal of Strength and Conditioning Research (in press)
Vikne, H., Refsnes, P.E., Ekmark, M., Medbo, J.I., Gundersen, V., Gundersen, K. (2006) Muscular performance after concentric and eccentric exercise in trained men. Medicine and Science in Sports and Exercise, 38(10):1770-1781
Vogt, M., Hoppeler, H.H. (2014) Eccentric exercise: Mechanisms and effects when used as a training regime or training adjunct. Journal of Applied Physiology, 116: 1446-1454
Watsford, M., Ditroilo, M., Fernandez-Pena, E., D’Amen, G., Lucertini, F. (2010) Muscle stiffness and rate of torque development during sprint cycling. Medicine and Science in Sports and Exercise, 42(7): 1324-1332
Weyand, P.G., Sternlight, D.B., Bellizzim M.J., Wright, S. (2000) Faster top running speeds are achieved with greater ground forces not more rapid leg movments. Journal of Applied Physiology, 89(5): 1991-1999
Weyand, P.G., Sandell, R.F., Prime, D.N.L., Bundle, M.W. (2010) The biological limits to running speed are imposed from the ground up. Journal of Applied Physiology, 108: 950-961


Sunday, 29 January 2017

A Coaches' Guide to Strength Development Part IX: Eccentric Strength Training Part I - a guest-post by Dr Angus Ross

photo courtesy justynwarner.com
Eccentric Training – An Introduction by Matt Jordan, PhD:

If we were discussing a personality trait, ‘eccentric’ would characterize an odd or strange individual. Some might characterize Stu as being eccentric. If we were discussing an object, ‘eccentric’ would refer to its non-centered position. However, when it comes to muscle, the term ‘eccentric’ refers to an action whereby a muscle is lengthened under tension.

Not only are eccentric muscle actions often used by strength coaches as a potent training stimulus to strengthen skeletal muscles but they have also posed unique challenges to the scientific theories underpinning muscle contraction.

In his seminal paper in 1957, Andrew Huxley, the father of the cross bridge model of muscle contraction, noted the discrepancies between his mathematical models of muscle contraction and the empirical evidence obtained during lengthening contractions. The slope of the force-velocity relationship just beyond maximum isometric force was much steeper for lengthening contractions compared to shortening contractions and the energy liberated during lengthening contractions was less than his mathematical models predicted.

Additionally, when an active muscle is forcibly stretched to a new length, the new tension that is generated exceeds the value obtained at that length if no pre-stretch occurred. This phenomenon termed ‘residual force enhancement’ is another fundamental muscle property related to lengthening or eccentric contractions that is not well explained by existing scientific theories on skeletal muscle contraction.

In his book “Reflections on Muscle” published in 1980, Huxley discusses eccentric actions frequently. Huxley remarks: “I imagine that special features have been evolved which allow this elongation (of muscles) to take place without damaging the muscle … I suspect that many of the unexplained phenomena, such as those I have just described here (associated with muscle lengthening) are related to these special features, and have little relation to the processes that take place during shortening”.
It seems the nature of eccentric muscle actions are mysterious and might contain hidden secrets. Is this why experienced strength coaches find so much potential with eccentric training methods? Because if one thing is clear, eccentric training methods are of critical importance for preparing the elite athlete.

In these next two blog-posts, Dr Angus Ross delves into the practical applications and considerations for eccentric training. Having read these two posts, I can tell you that what you are about to read will be an excellently written and well-referenced series on why and how eccentric training methods should be used.

photo courtesy justynwarner.com

Part I: Eccentric Strength Training – Dr Angus Ross

This is the first of my two guest blogs on Eccentric (ECC) training, with Part I covering some background in regards to some of the concepts of ECC training for speed and power sports, and Part II covering some practical application and programming options.

As some brief background, my work is predominantly in New Zealand Olympic power sports i.e. a relatively small pond with limited depth, where more often than not our top athletes are relatively unchallenged for their Olympic berths. The benefit of this, however, is that we are lucky in being able to plan in the long- to medium-term for performance at pinnacle events. With that in mind, it may give some perspective to my use of eccentric training, and where I see it fitting in during a training block. Nevertheless please consider my proposed approach may not suit dissimilar competition schedules – though I do hope some of the principles are of value.


Eccentric Strength Training:

As has been mentioned in previous posts in this series, ‘eccentric-emphasized’ strength training involves yielding to – or lowering of – typically supra-maximal loads (relative to the concentric phase). There are a variety of methods for inducing ECC overload. This is a growing area in both sport-related and commercial fitness with an increasing number of ECC-based devices coming on the market; nonetheless there are also many options that can be done on standard equipment with a little imagination.


Why use ECC training?

There are lots of pros and cons to be considered as ECC training has the potential to strongly influence other training units; it needs to be used judiciously to create a positive impact on performance. The text to follow is largely based around the direct performance implications with respect to ECC training and the potential to develop a contractile system that is both stronger and faster. Perhaps the Holy Grail is using ECC training to move the force/velocity curve upwards and to the right with particular gains at high speed (see Figure 1). We may not quite be there yet in terms of complete understanding – but options are discussed in the text to follow. There remains much to be learnt on many fronts with ECC training, and it should be noted that ECC work is also heavily prescribed in tendon, rehabilitation and therapeutic work, so it has training implications well beyond the scope of this post.


POTENTIAL BENEFICIAL MUSCULO-TENDINOUS ADAPTATIONS


Faster muscle contractile properties:

Training muscle to contract harder and faster has obvious performance benefits for many sports. Evidence suggests that there are at least two potential mechanisms by which ECC training may be able to up-regulate the contractile speed of muscle:

Fibre type shifts: In contrast to most isotonic resistance training studies (which typically show a decrease in the percentage of the fast IIx myosin or IIb muscle – Harridge, 2007), ECC training may offer the opportunity to shift myosin in the opposite direction – i.e. towards fast twitch (FT). The evidence is by no means conclusive but there is just enough of it to make it an interesting option! 

For example:

Eight-weeks of high speed (180 degrees per second) ECC elbow flexor work significantly increased the percentage of FT & particularly IIb muscle fibres (Paddon-Jones et al., 2001), and a single bout of ECC exercise caused the proliferation of muscle satellite cells towards FT fibre type (IIx) following (Cermak et al., 2013) and or greater anabolic signalling of FT muscle than in slow twitch muscle (Tannerstedt et al., 2009)

Increasing relative cross sectional area of FT muscle with ECC resistance training (as compared to concentric only training) (Vikne et al., 2006; Hortobagyi et al., 1996)

Number of sarcomeres in series: Eccentric training also has potential for increasing contractile velocity by adding sarcomeres in series (Lynn & Morgan 1994 ; Friden et al., 1984) and increasing muscle fascicle length (Timmins et al., 2015; Franchi et al., 2014; Seynnes et al., 2007; Butterfield et al., 2005). Evidence suggests that more sarcomeres in series has an additive effect on contraction velocity – perhaps having a greater effect on contractile speed than fibre type (Sacks & Roy, 1982). Not surprisingly, muscle fascicle length is positively correlated with sprint running performance in some papers (Kumagai et al., 2000); although given the multi-factorial nature of sprinting, it doesn’t discriminate between good sprinters (10.70s 100m runners) and elites (~10.30s) (Karamanidis et al., 2011). Notably, not all studies concur with regard to greater changes in fascicle length and sarcomeres in series with ECC training. Furthermore, and somewhat counterintuitively, even when significantly greater gains in fascicle length have been demonstrated post-ECC work, immediate performance gains especially in concentric (CON) tasks are not always forthcoming – more on this later.


Additional Muscle/Tendon Architecture changes:

Muscle Adaptation: The greater training loads of eccentric exercise promote greater hypertrophy (and in the most part strength – depending on how it is being measured) adaptations for an equal period of training than that observed from conventional weight training (Higbie et al., 1996; Farthing et al., 2004; Roig et al., 2009). Similarly, greater increases in collagen expression within muscle also occur with ECC training as compared to CON training (Heinemeier et al., 2007).

Tendon – changes in cross sectional area (CSA)? Some evidence suggests that the distal part of the musculo-tendinous unit is where the greatest stress and adaptation occurs with ECC training (e.g. Franchi et al., 2004; Seger et al., 1998), and certainly changes do occur with tendon stiffness (see section below). Perhaps due to the relatively avascular nature of tendons, however, there is less evidence on direct changes in tendon CSA with short term ECC training interventions.

Fascia – Anecdotally at least, it appears that fascia also responds and develops in response to tension (Schliep & Muller 2013), and hence the high stresses experienced in ECC exercise means it is likely to be a potent stressor for remodeling fascia. The increase of collagen expression in response to ECC training seen in muscle work (see muscle adaptation point above) appears to corroborate this assumption.

Figure 2: Torque exerted by the knee-extensor muscles and EMG of Vastus Lateralis (from Tesch, et. al, 1990)

Stiffness/Compliance adaptations:

Greater muscle/tendon stiffness: It is beyond the scope of this blog-post to go into the topic of stiffness in any great detail. In brief however, stiffness is the resistance to change in length of a tissue or joint (or series of joints – like a leg) and there are active (affected by muscle activation) and passive elements (the intrinsic stiffness qualities of the tissue) that affect the overall stiffness outcome. Noting that it is possible to be simultaneously both very stiff and very elastic – think of a heavy duty spring that returns nearly all of the energy when it is compressed. It is interesting to note that certain components of stiffness are related positively to performance outcomes in stretch shortening cycle (SSC) sports, with great jumpers and sprinters typically displaying great stiffness qualities. Greater stiffness potentially increases the rate of force application – a particularly critical factor in high speed sports with limited time to maximize force application. An obvious example of this would be sprinting, given both the brevity of ground contact time in sprint running and the importance of massive forces to increase speed (Weyand et al., 2000 & 2010). Gains in leg-spring stiffness have also been positively associated with increased running economy in endurance runners (Albracht & Arampatzis, 2013), and improved peak power in sprint cyclists (Watsford et al., 2010). As with most things however, more stiffness ad infinitum is not always better – i.e. you need to be able to actually compress a spring if you want to get any rebound out it, so it’s good to measure and know how ECC training affects the stiffness (both active and passive) of the leg.


So what happens to stiffness with ECC training?

ECC training appears to increase leg spring stiffness significantly more than concentric only work (Elmer et al., 2011; Lindstedt et al., 2001). It is likely that the ECC training effects both active (i.e. neurally driven – e.g. co-contraction, decreased inhibition, etc.) as well as passive elements of stiffness. Where in the ‘series elastic component’ (muscle + tendon) the passive adaptations occur it is not entirely clear – though the likelihood is that both muscle and tendon are modified with ECC loading. Some evidence suggests that high load ECC work particularly may increase the stiffness of the tendon (Malliaras et al., 2013; Foure et al., 2013) and as alluded to in the previous section, potentially there may also be increased collagen expression within the muscle. In practical terms, ECC training can be used to directly target increases in stiffness – potentially a genuine performance enhancer – particularly for a highly compliant or ‘floppy’ athlete that may have great elastic qualities but sub-optimal speed and slow ground contact times.

photo courtesy justynwarner.com

POSITIVE APPLIED PERFORMANCE ADAPTATIONS

Performance adaptations as result of an ECC training intervention are clearly what most of us as coaches or practitioners are interested in. Obviously the performance outcomes are dictated by both the soft tissue adaptions discussed above as well as neural adaptations. Evidence suggests that ECC contractions differ from CON with both greater cortical activation (Fang et al., 2001) and lesser muscle activation despite greater force (see Figure 2). With ECC training, an athlete learns to cope with severe ECC stress and thus have an improved ability to activate agonists (via adaptation in muscle spindle feedback), decreased antagonist co-contraction as well as potential decreased agonist inhibition from Golgi tendon organs. So the neural alterations in conjunction with the musculo-tendinous adaptations can give rise to our primary objectives of performance gains. In addition to strength adaptations already mentioned these can include:

Stretch Shortening Cycle (SSC) performance: Eccentric strength is positively related to power output in SSC performance (Miyaguchi et al 2008). Similarly, gains from both purely eccentric loading (Elmer et al., 2011; Linstedt et al., 2001) and eccentric-accentuated jump training (Sheppard et al., 2008 – see Figure 3) have shown superior vertical jump adaptations in comparison to concentric only or traditional jump training. Eccentric-accentuated strength training also appears to facilitate gains in maximum velocity sprint running (Askling et al., 2003) as well as acceleration (30m time) and drop jump performance (Liu et al., 2013). At this stage, it is unclear whether the speed of the ECC intervention is critical for the SSC adaptations. It is, however, worth noting the Elmer research (eccentric cycling) and some of the passive leg press training from the Taiwan group (Liu et al., 2013) (see www.youtube.com/watch?v=9sjkWTNP4n4) would be described as high speed ECC dominant training.

Concentric (CON) Performance/Power: It could be reasonably expected that the potential gains in muscle contractile speed (detailed above) would be mirrored in performance in concentric performance. However gains in ‘concentric only’ power e.g. cycling, swimming, kayak, & perhaps rowing and-or isometric force from eccentric training are not always immediately forthcoming from a period of eccentric loading (Gross et al., 2010; Elmer et al., 2011; Leong et al., 2014). Indeed the data from Leong and associates (2014) demonstrated that there may be a delay in CON performance adaptation with ECC training. Notably, CON power production was greater 8 weeks post cessation of an ECC training block than it was when tested 1 week after completing the ECC training.

With that in mind, potential negatives of eccentric loading (see below) need to be factored in before adopting an eccentric training protocol in CON sports.

Figure 3: accentuated eccentric jump squat

POTENTIAL CONTRAINDICATIONS OF ECCENTRIC TRAINING

Muscle Damage/Soreness: As alluded to above, part of the mechanism of adaptation to ECC training may be related to greater muscle damage that occurs – with evidence suggesting that FT fibres in particular get hammered from ECC stress (Friden et al., 1984; Linnamo et al., 2000). Similarly, we see greater delayed on-set of muscle soreness (DOMS) with ECC loading than that observed from conventional strength training (at least for initial sessions). If muscle tissue is stressed too severely, performance may be substantially impaired for several weeks or longer (Mackey et al., 2004; Sayers & Clarkson, 2001). This is potentially reflected in the delayed CON performance adaptations discussed above.

Fascial damage/pain response: Evidence suggests that much of the DOMS response to ECC work may be related directly to damage to, or inflammation of, the fascial network (Lau et al., 2015; Gibson et al., 2009). My take on both the fascial pain response and remodeling that likely occurs is that acutely there will be changes in afferent feedback during exercise and it may mean it is difficult to maintain an optimal technical model in your sport during the initial phases of a heavy ECC training phase. Acknowledging this, and working with and around it, becomes a critical consideration in a training plan.

photo courtesy justynwarner.com

Summary & Recommendations: Damage and inflammation occurs with ECC training at both a muscle (especially FT muscle) and fascial level, which may negatively affect performance in the short term especially in high tension and/or speed ballistic tasks. With that in mind, my recommendation is that ECC training should be commenced using conservative load assignments, using limited sets and reps on training initial sessions to minimize DOMS – noting there is a strong protective effect against DOMS with one or two sessions of graduated ECC loading. In my experience, such an approach minimizes the disruption to other training units which can be adversely affected, and total training stress can be progressed relatively rapidly over days and weeks.


ADDITIONAL OBSERVATIONS

Mode-Speed Specificity: There is some suggestion in the ECC training literature that adaptations from ECC training are more mode- and speed-specific than equivalent concentric training (Roig et al., 2009). Given that the objective for most of us is to transfer strength gains to dynamic sport performance it is worth noting that higher speed ECC loading (180o s-1 ) may give better adaptation in strength, hypertrophy and fibre-type than that seen in slower (~30o s-1) training (Farthing et al., 2004; Paddon-Jones et al., 2000).

My impression is that once some basic preparatory training has been done, adaptations to faster ECC work is likely to be a superior modality for athletes. It is apparent however, that much of the ECC strength training literature is somewhat lacking in ecological validity – i.e. what is done in research does not necessarily reflect general training practice. The vast majority of ECC studies (unlike in typical athlete training) do not combine the ECC loading with additional concentric training or applied SSC exercise, perhaps partially explaining the mode-specificity findings with ECC work. In one of the few studies that has combined ECC training with other modalities and applied testing, Cook and associates (2013) demonstrated additive performance gains in sprint running when ECC work was combined with over-speed running. Hence, results in applied tasks perhaps could-would be further enhanced with a concurrent training approach.

My recommendation would certainly not be to do exclusively ECC work in training (in the designated ECC phase), but rather to do it as the dominant modality in conjunction with some dynamic sport-specific training.

ECC force modulation and impact on performance: A further observation of ECC exercise is that athletes with the ability to accurately modulate eccentric force production may have a genuine advantage in certain sports. Vogt and associates (2014) noted a strong relationship between accuracy of force modulation on an eccentric recumbent bike and competitive slalom ski race performance. Similarly, some anecdotal evidence with multi-event athletes (decathlon & heptathlon) suggests that some of the very top performers are able to dampen or stiffen the leg spring to suit the demands of the event at hand to a greater degree than those athletes below medal level. Perhaps demonstrating superior control of ECC force modulation to optimize impulse or RFD depending on the constraints of the task. I would expect that elite performers in many team sports may also exhibit the same sorts of characteristics with the unpredictable nature of the contractile demands imposed on the athletes. To my mind at least, it makes sense that perhaps training the ECC qualities may both improve performance directly with regard to muscle strength and power qualities, and some of the rhythmic ECC training modalities (e.g. eccentric cycling, passive squatting) may also offer a motor learning benefit.

Ultimately, perhaps empowering athletes with the physical and neural tools to drive either the force-application or force-damping in a superior fashion to optimize performance in the specific task at hand.

Rest and Restoration vs Detraining: With the extreme muscle tensions produced with overloaded ECC training, clearly there are both potential negative and positive responses to such loading – and perhaps the optimal time of recovery post an ECC training phase will depend on the demands of the desired performance outcome, as well as the magnitude of the prior training stress. There is, however, some evidence to suggest that ECC training strength adaptations are relatively well preserved over up to 8 weeks, and appear more resistant to detraining than those from CON training (Colliander & Tesch, 1992). Notably however changes in fascicle length derived from ECC training appear less well maintained – with data suggesting that these may return to baseline after 28 days of no ECC stimulus (Timmins et al., 2015). Arguably, this muddies the water somewhat – as a coach you must weigh up the potential positive effects of rest on the improved ability to activate a muscle without inhibition, as well as possible shift towards type IIx myosin versus the potential negatives of a reduction of fascicle length and potential atrophy.

Figure 4: performance impact of eccentric training - overview

OVERALL SUMMARY

As summarized in Figure 4 above ECC training – and arguably fast ECC training in particular – appears to offer superior adaptations relative to traditional strength training for developing the anatomical tools for high speed contractions and robust delivery of force, particularly in SSC-dominant sports. However, muscle damage and resulting potential power impairment in the short- to medium-term needs to be factored in when planning the implementation of an ECC training intervention to maximize the transfer of power to applied performance. Needs of both the individual athlete and event performance must be considered in the taper to a major event.


Stuart McMillan:


I really want to thank Angus for his thoughts; there are few folks in the world who are as comfortable in academia as they are in the weight room, or on the track. Angus is definitely one of them, and I’m really grateful he agreed to write this section. Stay tuned for the next post, where Angus delves into the practical application of eccentric training; as well, I will share my own thoughts, and how they have developed over time.