Slow and eccentric strength training

Versión en español

I have really enjoyed your blog posts - I especially appreciate that you don't tell people only what to do or what not to do, but that you also give reasons which helps us go much farther in understanding our training. In that vein, I'm wondering if you can elaborate on why "perform slowly part of an exercise like pull-ups is against our interest" or "same goes for maintaining a fixed angle of the elbow until exhaustion" might be bad. It seems I've heard of so many climbers see positive benefits from slow negatives and lock-offs in improving pulling strength. Thanks again for your excellent posts! 
Randy (in Frequently Asked Questions about Progression and Finger Strength Training (III))


MY ANSWER
Hi Randy,
Thank you very much for your appreciation.
I enjoy explaining the way things work, firstly because that question is what drives me to research the topics that puzzle me; in my opinion this is also more honest, and makes for a better learning than just listing some recipes without justifying them. This way you have more information to decide for yourself whether to follow the advice an the way of carrying it out.
I'll answer your question in two entries that will deal with the following topics:
Intentionally slow strength training; execution speed of an exercise; eccentric training; and lock-off strength training or stopping at certain angles while doing pull-ups

Intentionally slow strength training
Performing your strength exercises intentionally at a low speed (or part of them, like the eccentric part of the motion when doing negatives, picture below) is a style inherited from bodybuilding, under the presumed justification that doing so will cause more damage to the muscle, which in turn will promote hypertrophy. 

Source:www.chanhassenfitnessrevolution.com

Nosaka and Newton (2002), found that it appears that extensive muscle damage may not be a prerequisite for muscle hypertrophy. In the only RCT (randomized controlled trial) carried out to this date that looks at this topic, Keeler et al. (2001) suggest that some hypertrophy can occur in initially untrained subjects with an intentionally slow training, but not as extensive as that resulting from heavy weight training (80% of 1 RM or higher, and 5-8 repetitions typically ).

On the other hand, some authors argue that a muscle that is under load for more time will increase in endurance. However, I have found only 1 peer-reviewed study that supports this, and it has to be noted that these gains were only tested doing an exercise with similar speed and duration than those used during the training phase. It remains to be seen if these gains would translate into a better performance when doing the actual moves of the sport.

Have you ever asked yourself whether the exercise you are doing, and how you are doing it, will help you climb better? source: http://robertsontrainingsystems.com

In mi opinion, it makes more sense for increasing muscular endurance to perform a higher number of repetitions with a normal speed restricted only by load or fatigue, than doing less repetitions at a deliberately lower speed.
Why? 
Because the latter means using lighter loads, and given that load has a direct association with muscle force production, the effect will be a smaller increase in strength and endurance.


For an athlete, going slowly on purpose, and not because of fatigue or due to our body weight being too high a load for that particular exercise, the result will be a development of slow-twitch fibers instead of fast-twitch fibers; the latter are associated to power, an so play an important role in our sport performance.

About the execution speed of an exercise
Given that power = force x velocity, when we apply the same force at a lower speed we are developing less power, so to maintain the power the force should be higher. For example, if we have great pulling strength and we do campus board with good holds or assisted pull-ups, we will be moving fast; if we do pull-ups with added weight we'll move more slowly; in both cases we are working our power, be it via increased velocity or via increased force.

Compared to slow velocities, moderate and fast velocities have been shown to be more effective for increasing the number of repetitions performed, work and power output, and volume ( Lachance and Hortobagyi, 1994; Morrissey and col, 1998 ), and for increasing the rate of strength gains (Hay and col, 1983).

Alex Puccio, Bouldering World Cup - Barcelona 2011
photo by David Munilla

You also mention slow negatives, in other words, doing just the eccentric phase of the exercise at a lower speed (coupled concentric-eccentric contractions). It's been suggested that this style only has an effect on "sarcoplasmic hypertrophy", the increase in volume of non-contractile proteins and sarcoplasm; this is why it is also known as "useless hypertrophy", because it is not associated to an increase in strength. This type of hypertrophy is typically seen in bodybuilders, in contrast with the useful hypertrophy that results from the training of weightlifters and powerlifters.

Probably the most famous bodybuilder of all time: Arnold Schwarzenegger.
Source: http://pictureland.info

A Weightlifter

Effects of eccentric training
Eccentric exercise creates greater force than concentric actions using less energy. Therefore, a person is capable of working with greater weight during an eccentric exercise. That's why eccentric training increases hypertrophy and muscle-strength significantly more than concentric training or coupled concentric-eccentric contractions, if one of the following conditions is met: 

• The load is between 100 and 140% of the maximum concentric force;
• There is a combination of eccentric (120-140%) and concentric (80%) phase in the same exercise (usually aided by other person or a machine).

Is this true?

Anyway, only really advanced athletes can benefit from an eccentric training, and always when the competition is far ahead, because the tensions generated are so high that the recovery period is long, and the risk of injury is high.

SOON:
Lock-off strength training or stopping at certain angles while doing pull-ups.

REFERENCES

• Gonzalez Badillo and Ribas, J (1996): Fundamentos del entrenamiento de la fuerza. Inde
• González-Badillo, JJ, and Izquierdo, M. (2008): Evaluación de la fuerza en el control del entrenamiento y el rendimiento deportivo. En Izquierdo, M. (editor); Biomecánica y Bases Neuromusculares de la Actividad Física y el Deporte. Panamericana
• Hay, J.G., Andrews, J.G. & Vaughan, C.L.(1983): Effects of lifting rate on elbow torques exerted during arm curl exercises. Medicine & Science in Sports & Exercise 15, 63-71
• LaChance, P. & Hortobagyi, T. (1994): Influence of cadence on muscular performance during push up and pull
  up exercises. J Strength Conditioning Res. 8: 76-79.
• Keeler, L. K., Finkelstein, L. H., Miller, W., & Fernhall, B. (2001): Early-phase adaptations of traditional-speed vs. superslow resistance training on strength and aerobic capacity in sedentary individuals. Journal of Strength and Conditioning Research, 15(3), 309-314.
• LaChance, P. & Hortobagyi, T. (1994): Influence of cadence on muscular performance during push up and pull
  up exercises. J Strength Conditioning Res. 8: 76-79.
• Morrissey MC, Harman EA, Frykman PN, Han KH.(1998): Early phase differential effects of slow and fast barbell squat training. Am J Sports Med. 26:221-30.
• Nosaka K, Newton M. (2002): Repeated Eccentric Exercise Bouts Do Not Exacerbate Muscle Damage and Repair. J Strength Cond Res. Feb;16(1):117-122. 
• Stone, M.H., Stone, M. and Sands, W.A. (2007): Principle and Practice of Resistance Training. Human Kinetics