Even if strength coaches understand the effects long, slow distance training for intermittent type sports,the larger issue may be convincing sport coaches to eliminate long distance fitness tests that coerce athletes into training for the tests, instead of competition. Here are some notes on the physical requirements for soccer and the consequences of endurance training.
Physical requirements and implications of training mode
A summary of the physical demands of soccer may seem rudimentary for strength and sport coaches. It is more important to connect the requirements that I outline here with the consequences of continuous endurance training that I list in the proceeding section.
• Soccer players must be able to accelerate. The ability to accelerate rapidly is critical as most of the sprints during a soccer match only cover between 10-20 meters.
• Lower body power (commonly measured by jumping ability) is traditionally a good indicator of acceleration ability.
• In order to be powerful, an athlete must possess sufficient relative strength. A resistance-training program designed to enhance maximum strength will improve speed in most cases.
• Speed and power is not only determined by muscular architecture (size), but the ability to quickly produce energy for muscular contraction. Within a muscle, we use stored ATP (energy), creatine phosphate (which helps quickly regenerate ATP), and glucose (via anaerobic glycolysis). It’s now estimated that these three sources contribute more simultaneously than sequentially during near maximal exercise (4), this will be important in a minute.
• For soccer-specific performance, athletes must be able to recover from bouts of high intensity running. This means that energy-yielding substrates must be restored and metabolites that interfere with muscular contraction must be buffered.
• Soccer players must not only be able to accelerate, but also decelerate rapidly. Deceleration and change of direction can greatly increase the demand of a conditioning program,
It may be the size of the field, the length of the match, or the deceiving analysis that soccer players cover 4-6 miles over the course of a match that skews coaches’ perspectives. Like I said, this stat is misleading. I expect most average athletes could trek 5 miles in 90 minutes. Again, it’s how your athletes cover that distance that matters.
Long distance running or traditional endurance training induces many physical adaptations that interfere with the abilities necessary for success in soccer. A review of these consequences includes:
• Long distance running wreaks overuse injuries, as does any repetitive event (9) (↑ risk of injury).
• Endurance training elicits numerous adaptations that lead to the development and preferential recruitment of slow-twitch muscle fibers (7, 8). As a result, dormant fast-twitch muscle fibers atrophy and total muscular cross sectional area decreases (↓ strength and power).
• Muscle cells enhance their ability to utilize fat as a fuel source. As a result, glycolytic enzymatic function decreases (6) (↓ contribution from glycolysis, which we’ve already discussed, is an important contributor to energy production at the initiation of near maximal exercise (7)).
• Likewise, endurance training impairs strength at high speeds of muscular contraction. Endurance training has been to shown to decrease performance during isokinetic testing at high angular velocities and decrease performance in field tests such as the vertical jump (which is a solid indicator of acceleration ability) (8).
• Endurance training may not enhance muscle-buffering capacity. There is conflicting evidence, as both aerobic and intermittent training appear to enhance this capacity in untrained individuals, but as training status increases, the benefits from endurance training diminish (↓ recovery-capacity from high intensity sprints) (10).
• Research has consistently demonstrated that concurrent strength and endurance training interferes with the development of strength. Both same-day (lifting and running) and alternate-day (lift on one day, run on the next) training methods impair strength development (8). In this case, a good deed does not erase a bad one.
In general, long distance, endurance training interferes with every physical capacity we’ve determined to be essential for soccer performance.
7. Plisk S. S. Anaerobic metabolic conditioning: A brief review of theory, strategy and practical application. Journal of Applied Sport Science Research, 5:22-34, 1991.
8. Leveritt M., Abernethy P. J., Barry B. K., and Logan P. A. Concurrent strength and endurance training: A review. Sports Med, 28:413-427, 1999.
9. Ryan M. B., MacLean C. L., and Taunton J. E. A review of anthropometric, biomechcanical, neuromuscular and training related factors associated with injuries in runners. International SportMed Journal, 7:120-137, 2006.
10. Little T., and Williams A. G. Effects of sprint duration and exercise: rest ratio on repeated sprint performance and physiological responses in professional soccer players. Journal of Strength and Conditioning Research, 21:646-648, 2007.