Concurrent strength and endurance training - A review

Concurrent strength and endurance training appears to inhibit strength deve lopment when compared with strength training alone. Our understanding of th e nature of this inhibition and the mechanisms responsible for it is limite d at present. This is due to the difficulties associated with comparing res ults of studies which differ markedly in a number of design factors, includ ing the mode, frequency, duration and intensity of training, training histo ry of participants, scheduling of training sessions and dependent variable selection. Despite these difficulties, both chronic and acute hypotheses ha ve been proposed to explain the phenomenon of strength inhibition during co ncurrent training. The chronic hypothesis contends that skeletal muscle can not adapt metabolically or morphologically to both strength and endurance t raining simultaneously. This is because many adaptations at the muscle leve l observed in response to strength training are different from those observ ed after endurance training. The observation that changes in muscle fibre t ype and size after concurrent training are different from those observed af ter strength training provide some support for the chronic hypothesis. The acute hypothesis contends that residual fatigue from the endurance componen t of concurrent training compromises the ability to develop tension during the strength element of concurrent training. It is proposed that repeated a cute reductions in the quality of strength training sessions then lead to a reduction in strength development over time. Peripheral fatigue factors su ch as muscle damage and glycogen depletion have been implicated as possible fatigue mechanisms associated with the acute hypothesis. Further systemati c research is necessary to quantify the inhibitory effects of concurrent tr aining on strength development and to identify different training approache s that may overcome any negative effects of concurrent training.