Individuals who participate in endurance activities like distance running, biking, nordic skiing and swimming are often hesitant to strength train for concerns about gaining non-functional muscle mass or restricting sport specific training time. Physiological adaptations are quite specific to the demands of the training program. For instance, strength training produces enhanced motor control, improved rate of force production, potentially decreased mitochondrial volume density and an increase in associated anaerobic enzyme and hormonal activity. There is also an associated adaptation in the anatomy of the individual’s connective tissue, bones, ligaments and tendons. On the other hand aerobic training can lead to increased capillary and mitochondrial density, more effective transport of the oxygen and carbon dioxide, improvements in blood volume leaving the heart and an improvement in body composition.
If you are an endurance athlete you know that the intensity of both training and racing can change quickly due to hill climbs, tactics, surges in pace and sprint finishes. It is definitely advantageous to have the ability to keep pace for whatever reason. Being able to stay with the pack means possessing the ability to go anaerobic, recover and if necessary go anaerobic again multiple times.
Recently there has been a focus on strength training for endurance activities. Combining both endurance activities and strength training is referred to as “concurrent training.” A growing body of evidence supports the utility of concurrent training for endurance athletes.
Esteve-Lanao et. al. determined running-specific strength training minimizes the loss of stride length that typically occurs in endurance runners during fatiguing running bouts. Esteve-Lanao, et. al. Running specific, periodized strength training attenuates loss of stride length during intense endurance running. J Strength Cond Res 22: 1176-1183, 2008.
Paavolainen et al. found that substituting 33% of endurance training time with explosive strength training activity in elite male cross country runners’ programs for 9 weeks enhanced 5-km run time and running economy (metabolic activity associated with a given running velocity) without a change in VO2max. These findings indicate that explosive resistance training can improve running economy and performance as a consequence of enhanced neuromuscular functioning. Paavolainen, L. et. al. Explosive strength training improves 5-km running time by improving running economy and muscle power. J. Appl. Physiol. 86:1527-1533. 1999.
Johnston, et. al. studied a group of university female cross-country runners and found that 10 weeks of resistance training improved running economy through enhanced leg strength. Johnston, R.E., et. al. Strength training in female distance runners: Impact on running economy. J. Strength Cond. Res. 11:224-229. 1997.
Millet et al. found that a combination of endurance training and heavy weight training in well-trained triathletes enhanced running economy and leg strength and power, and had no negative effect on aerobic capacity. Millet, G.P., et. al. Effects of concurrent endurance and strength training on running economy and VO2 kinetics. Med. Sci. Sports Exercise. 34:1351-1359. 2002.