Context: Many elite athletes use increased daily training frequencies as a means to increase training load without substantial published literature to support this practice.
Purpose: To compare the physiological responses to twice- and once-daily training sessions with similar training volumes.
Methods: Ten nationally competitive male weightlifters (age 20.5 +/- 1.2 y, body mass 92.9 +/- 23.6 kg, training history 5.5 +/- 1.5 y) were matched on body mass and training experience, then randomly assigned to train either once or twice daily for 3 wk. Isometric knee-extension strength (ISO), muscle cross-sectional area, vertical-jump peak power, resting hormone concentrations, neuromuscular activation (EMG), and weightlifting performance were obtained before and after the experimental training period.
Results: All dependent measures before the training intervention were similar for both groups. A 2-way repeated-measures ANOVA did not reveal any significant main effects (group or trial) or interaction effects (group x trial) for any of the dependent variables. There were also no significant group differences when parameters were expressed as percentage change, but the twice-daily training group had a greater percentage change in ISO (+5.1% vs +3.2%), EMG (+20.3% vs +9.1%), testosterone (+10.5% vs +6.4%), and testosterone:cortisol ratio (-10.5% vs +1.3%) than did the once-daily training group.
Conclusions: There were no additional benefits from increased daily training frequency in national-level male weightlifters, but the increase in ISO and EMG activity for the twice-daily group might provide some rationale for dividing training load in an attempt to reduce the risk of overtraining.