PLASTICITY OF RESPONSE TO EQUAL QUANTITIES OF ENDURANCE TRAINING SEPARATED BY NON-TRAINING IN HUMANS

1. The pattern of elevation of several serum biochemical indices (BL) of training stress (creatine kinase, CK; lactate dehydrogenase, LDH; a spartate aminotransferase, AST, Ca2+; urate, Ur; urea, U; total protei n, Prot; cholesterol, C) were measured serially through two extended p eriods of training, including taper (50 days each) separated by a peri od of complete non-training (90 days) in two male subjects. 2. The pat terns of variation in BI were compared with similar variation in eleme nts of a two compartment model predicting performance from training. 3 . These elements arbitrarily described as Fitness [g(t)] and Fatigue [ h(t)] were estimated daily from a daily training impulse [w(t)] define d from the duration time and heart rate elevation of an individual in a training session. 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. performance p(t) when iteratively modelled against a Criterion runnin g Performance, Cp(t) measured serially throughout training, over a sta ndard distance, then defines the pattern of variation in the elements g(t) and h(t) (Morton er al., 1990). 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) wh ich mirrored the time-course pattern of h(t), the fatigue element of t he dose/response model of training, with a slight phase delay. 7. Thus ESEA was already declining during hard training. 8. During the taper period ESEA declined rapidly to base line. This response was remarkabl y symmetrical in each, separate training period. 9. The Criterion runn ing performance (CP) declined during hard training and rebounded throu ghout the taper period reaching an asymptote before beginning to decli ne again as training fitness [g(t)] was lost, although the fatigue [h( t)] state was now minimal. 10. Serum Prot, U, Ur respectively were als o elevated throughout hard training, first following the hypothesized h(t) curve but showing a biphasic response, declining during the later phase of hard training, and rising again during taper. 11. The symmet ry of response of these indices in each period was less evident than t he 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.