DEVELOPING EXPLOSIVE POWER Dr. Adam Storey Lead Strength & Conditioning Specialist for Athletics NZ OVERVIEW How Strong is Strong Enough? Strength spectrum & strength in a sporting context. Explosive Strength Deficit (ESD). Resistance Training to Increase Power Output. Velocity based training. Double day training. BACKGROUND Coach for the NZ Weightlifting team since 2008 2010 Commonwealth Games 2012 London Olympic Games 2014 Commonwealth Games Strength & power consultant to a number of sports teams. Lead S&C Specialist for Athletics NZ. PhD Exercise Physiology Molecular and neuromuscular responses and adaptations to high-power, high-intensity resistance exercise in competitive weightlifters and resistance trained adults.
BACKGROUND PhD Student: Intra-session Auto-regulation in Strength Training. Masters Students: The Biomechanical and Neuromuscular Influence of Weighted Vest Resistance on the Performance of the Power Clean in Resistance Trained Adults. The Effect of a High-Fat, Low-Carbohydrate Diet on Body Composition and Muscular Performance in Competitive Strength and Power Athletes. The Effect of Olympic and Traditional Resistance Training on Golf Club Head Speed in Elite Amateur Golfers. STRENGTH VS. POWER STRENGTH: Maximal force or tension developed by a muscle group usually tested just before an isometric contraction. POWER: A function of work/time and maximal power output is said to occur between loads of 30%- 45% of 1RM 1 STRENGTH SPECTRUM Strength: Ability of a given muscle to generate force (>1%) Maximal Strength: MVC against an external load (95%-98%) Competitive Strength: Heightened setting (99%) Maximal Maximorum: Maximal force generated usually under involuntary muscle stimulation (100%) 2.
STRENGTH IN A SPORTING CONTEXT Specific Maximal Force (F m ): Maximal force attained in a given movement under specified conditions (i.e. force exerted on a 7kg shot during the delivery phase) 3. Absolute Maximal Force (F mm ): Maximal force generated in favorable conditions. STRENGTH IN A SPORTING CONTEXT Athletes will typically train absolute maximal force (F mm ) as a means to their specific maximal force (F m ). F mm can not be attained instantly and takes ~0.3-0.4secs to be generated 3. However, in many athletic movements, the duration when maximal force should be generated is <0.3secs. STRENGTH IN A SPORTING CONTEXT Sport & Motion Time (sec) Athlete & Performance % of World Record Sprint Take Off 4 0.101 (male) M: Mean 100m record 10.62s 89 0.108 (Female) F: Mean 100m record 12.22s 84 High Jump Take Off 5 0.15-0.23 (Male) M: 2.34-2.38m 0.14-01.18 (Female) F: 1.96-2.05m 96-97 94-98 Javelin Delivery 7 0.12 M: release velocity 30m/s, 80m throw 81 Shot Put Delivery 8 0.22-0.27 M: 19.60-21.35m 85-92 Therefore, we are typically not limited by our force generating ability but more so by our ability to utilize force RAPIDLY.
EXPLOSIVE STRENGTH DEFICIT In many sporting situations, athletes do not have sufficient time to produce F mm. F mm F m ESD % = X 100 F mm F mm = Absolute Maximal Force F m = Specific Maximal Force Therefore, ESD amounts to ~50% F mm EXPLOSIVE STRENGTH DEFICIT Elite shot putters impart ~500-600N of force to the shot during throws of 20-21m 3. (WRs: = 23.12m, = 22.63m). These athletes typically bench press 220-240kg, thus exerting a force of 1,070-1,176N with EACH ARM 3. Therefore this represents ~50% of their F mm. HOW MUCH STRENGTH IS NECESSARY? However, Moss et al. 1997 showed a strong correlation between PP at 2.5kg and 1RM performance which does indicate that at relatively light weights, 1RM still has considerable influence on power production. Seyfarth et al. (2000) using various modeling techniques, they have indicated that maximum strength is a primary factor in jumping performance. Eccentric strength was shown to be more important than factors such as tendon compliance or muscle contraction velocity.
TRAINING FOR THE CORRECT ADAPTATION VELOCITY BASED TRAINING Basis: An athlete s daily training load for a given exercise is determined by their barbell velocity for that particular exercise on that given day. Advantage: By knowing the speed of the lift, the coach can adjust the weight of the bar accordingly. Equipment: Linear position transducer VELOCITY BASED TRAINING Considerations: VBT training is measuring power output, not necessarily strength. A week to week fluctuation in weight doesn t mean the athlete is getting stronger or weaker. It is more an indication of the current state of their neuromuscular system. Training Methods: Specific number of reps and sets that are performed within a target velocity range and the training load is adjusted based on velocity. Training load remains the same and there is a target number of sets that need to be performed but the number of reps performed in each set is determined by velocity keep going until the velocity drops below 90% of the best repetition!
Exercise Target Velocity (m/s) Snatch power shrug 1.45 Snatch high pull 1.81 Snatch from floor 1.52 1.67 Hang snatch 1.35 1.96 Power clean 1.2 1.32 Hang clean 1.3 1.4 Power shrug 1.15 Power pull 1.38 Bench press (dynamic) 0.8 1.0 Squat (dynamic) 0.8 1.0 Speed-strength 1.0 1.5 ~90-95% max 0.45 0.58 1RM 0.3 0.35 Velocities based off the work of Dr. Bryan Mann University of Missouri VELOCITY BASED TRAINING FOR FREE? GymAware sensor: $2495 AUD (Ex GST) with free shipping worldwide. http://youtu.be/4xmfy_wy_r0 DOUBLE DAY TRAINING Is it worthwhile? How should the sessions be structured?
Cook et al. 2003 Sprints (5 x 40m) or weights (3RM squat and bench) were performed in the morning. DOUBLE DAY TRAINING The circadian decline in testosterone production was offset by AM training but it is unclear if there is a causal effect to performance DOUBLE DAY TRAINING - OW have the ability to sustain PF across 2 high-intensity sessions. - However, both groups have the ability to sustain PRFD. - Implications to training? SUMMARY We are typically not limited by our force generating ability but more so by our ability to utilize force RAPIDLY. Maximum strength (along with eccentric strength) is a primary factor in jumping performance. VBT may enable athletes to focus on developing explosive force in training. Double day training is a viable option.
Questions? REFERENCES 1. Izquierdo, M., Häkkinen, K., Gonzalez-Badillo, J. J., Ibáñez, J., & Gorostiaga, E. M. (2002). Effects of long-term training specificity on maximal strength and power of the upper and lower extremities in athletes from different sports. European Journal of Applied Physiology, 87(3), 264-271. 2. Zatsiorsky, V. M. (1995). Science and practice of strength training, human kinetics, campaign IL: Illinois. 3. Zatsiorsky, V. M. (2003). Biomechanics of Strength and Strength Training. In P. V. Komi (Ed.), Strength and Power in Sport (Second ed., Vol. 3, pp. 439-487). Oxford: Blackwell Science. 4. Mero, A., & Komi, P. V. (1986). Force-, EMG-, and elasticity-velocity relationships at submaximal, maximal and supramaximal running speeds in sprinters. European Journal of Applied Physiology, 55(5), 553-561. 5. Dapena, J. (2000). The high jump. Biomechanics in Sport: Performance Enhancement and Injury Prevention, 284. 6. Brüggemann, G. P. (1994). Biomechanics of gymnastic techniques. Sport Sci Rev, 3(2), 79-120. 7. Bartonietz, K. (2000). Javelin throwing: an approach to performance development. Biomechanics in Sport: Performance Enhancement and Injury Prevention, 401 434. 8. Lanka, J. (2000). Shot putting. Biomechanics in Sport, 435-457. 9. Moss, B. M., Refsnes, P. E., Abildgaard, A., Nicolaysen, K., & Jensen, J. (1997). Effects of maximal effort strength training with different loads on dynamic strength, cross-sectional area, load-power and load-velocity relationships. Eur J ApplPhysiolOccup Physiol, 75(3), 193-9. 10.Seyfarth, A., Blickhan, R., & Van Leeuwen, J. (2000). Optimum take-off techniques and muscle design for long jump. Journal of experimental biology, 203(4), 741-50. 11.Cook, C. J., Kilduff, L. P., Crewther, B. T., Beaven, M., & West, D. J. (2013). Morning based strength training improves afternoon physical performance in rugby union players. J Sci Med Sport. 12.Storey, A., Wong, S., Smith, H., & Marshall, P. (2012). Divergent muscle functional and architectural responses to two successive high intensity resistance exercise sessions in competitive weightlifters and resistance trained adults. EurJ Appl Physiol, 112(10), 3629-39.