Plasticity of response to equal quantities of endurance training separated by non-training in humans

Abstract

1. 1. The pattern of elevation of several serum biochemical indices (BI) of training stress (creatine kinase, CK; lactate dehydrogenase, LDH; aspartate aminotransferase, AST, Ca 2+; urate, UR; urea, U; total protein, Prot; cholesterol, C) were measured serially through two extended periods of training, including taper (50 days each) separated by a period of complete non-training (90 days) in two male subjects. 2. 2. The patterns of variation in BI were compared with similar variation in elements of a two compartment model predicting performance from training. 3. 3. These elements arbitrarily described as Fitness [ g( t)] and Fatigue [ h( t)] were estimated daily from a daily training impulse [ w( t)] defined from the duration time and heart rate elevation of an individual in a training session. 4. 4. g( t) and h( t) were used to predict performance [ p( t)] which might be expected from the training undertaken. So that: p( t) = k 1 g( t) — k 2 h( t) where k 1 and k 2 are arbitrary constants. 5. 5. Performance p( t) when iteratively modelled against a Criterion running Performance, Cp( t) measured serially throughout training, over a standard distance, then defines the pattern of variation in the elements g( t) and h( t) (Morton et al., 1990). 6. 6. Hard training for 28 days and a succeeding 22 days of taper in each training period produced a rise and fall in elevated serum enzyme activity, ESEA, (CK, LDH and AST) which mirrored the time-course pattern of h( t), the fatigue element of the dose/response model of training, with a slight phase delay. 7. 7. Thus ESEA was already declining during hard training. 8. 8. During the taper period ESEA declined rapidly to base line. This response was remarkably symmetrical in each, separate training period. 9. 9. The Criterion running performance (CP) declined during hard training and rebounded throughout the taper period reaching an asymptote before beginning to decline again as training fitness [ g( t)] was lost, although the fatigue [ h( t)] state was now minimal. 10. 10. Serum Prot, U, Ur respectively were also elevated throughout hard training, first following the hypothesized h( t) curve but showing a biphasic response, declining during the latter phase of hard training, and rising again during taper. 11. 11. The symmetry of response of these indices in each period was less evident than the ESEA response. None of the BI patterns measured was in phase with g( t), all, seemingly, reflected the catabolic rather than the anabolic process of hard training.