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A loss in strength has been associated with unaccustomed bouts of eccentric exercise. In a study by Clarkson , using the forearm flexors, immediate strength losses were as much as 50%. Gradually strength is restored but even after 10 days a deficit remains. Studies have shown that muscle fibers are damaged by eccentric exercise. In biopsies taken 2 days after eccentric exercise, damage to the myofibrils has been observed, including; Z-line streaming, focal disturbances, and supercontracted sarcomeres (10). It is possible that strength losses are related to the damaged myofibrils. However, according to Friden et al. (10) myofibrillar damage is greater 2 days following eccentric exercise than immediately post exercise. This may indicate that strength losses are independent of myofibrillar damage.

It has yet to be determined whether the initial losses in strength are due to muscle damage, fatigue or a combination of both . However, another possibility may be the nervous system. A change in the neural activation patterns could occur that bypass the more severely damaged muscle fibers, thus limiting the number of available muscle fibers for any given contraction . Studies by Newham et al. (21) have shown altered EMG patterns immediately and up to 48 hours following eccentric exercise.

Another possible explanation for the prolonged strength loss may be that sarcomeres are stretched out by the lengthening action of eccentric exercise . If the lengthening action pulled some of the sarcomeres apart, it would decrease the overlap between the actin and myosin filaments thereby reducing the maximal number of cross bridges that could be formed . The ability to generate force (i.e. strength) may be reduced due to this change in sarcomere length. It has yet to be determined whether the recovery in strength and the return of the sarcomere to its pre-exercise length follow the same time period.

***NOTE Scientific  data, nomenclature Courtesy :Pizza, F. X., J. B. Mitchell, B. H. Davis, R. D. Starling, R. W. Holtz, and N. Bigelow. Exercise-induced muscle damage: effect on circulating leukocyte and lymphocyte subsets. Medicine and Science in Sports and Exercise, 1995.

ootball players need a combination of technical, tactical and physical skills in order to succeed. It is odd, therefore, that football research has tended to focus on technique and tactics, with little emphasis on how to develop the endurance and speed needed to become a better player.
In one of the few studies which has explored the link between endurance capacity and football performance, Hungarian researchers showed that the ranking among the four best teams in the Hungarian top division was reflected by their players’ average maximal oxygen-uptake

Some studies have also shown that footballers tend to cover less distance and work at lower intensities during the second half of games than during the first half. The logical interpretation of these findings is that fatigue is limiting the players and that if they were fitter they would perform more effectively in the latter stages of their matches. None the less, until now no investigation has clearly shown that improving aerobic capacity and overall fitness boosts performance on the football field.

Interval training also boosted the athletes’ overall ability to play at high intensity; after eight weeks of interval work, they were able to perform at an average of 85.6% of max heart rate during their games, compared with just 82.7% beforehand. Training group members also spent 19 minutes longer than controls in the high-intensity zone (i.e above 90% of max heart rate) during an actual game.

**note DATA COURTESY:  Science and Football, T Reilly, A Lees, K Davids, and WJ Murphy (Eds). London: E & F N Spon, 1988, pp 95-107