EXERCISE INTENSITY INCREASE IS HARDER THAN DURATION INCREASE
Rusko, H. K. (2004). Influence of increased duration or intensity on training load as evaluated by EPOC and TRIMPS. Medicine and Science in Sports and Exercise, 36(5), Supplement abstract 1023.
"The index of training load (TRIMPS) is calculated from the relative intensity and duration of exercise multiplied by a factor describing blood lactate (Bla) vs. relative intensity relation. Excess Post-exercise Oxygen Consumption (EPOC) also increases with the intensity and duration of exercise and can be used as a physiological variable to indicate the training load" (p. S144).
This study evaluated the effect of increased duration or intensity of exercise on training load as evaluated by EPOC and TRIMPS. Healthy physically active men (N = 8) performed three constant velocity running exercises on an inclined (3°) treadmill: 21 and 40 min at 9.3 km/h, 68% of vVO2max (CV2168% and CV4068%, respectively), and 21 min at 10.8 km/h, 79% of vVO2max. EPOC and TRIMPS were calculated from VO2 and RR interval data measured before, during and after exercises.
EPOC and TRIMPS correlated significantly with each other (r = 0.80), with peakHR (r = 0.62 and 0.87) and with BLa (r = 0.68 and 0.74), respectively. Neither EPOC nor TRIMPS correlated with peakRPE during the exercises.
Implication. Increase in exercise intensity induces greater increments in training load than an increase in training duration. TRIMPS is more sensitive to training intensity than EPOC.