Assessment and characterization of physiological and biomechanical responses to CrossFit® benchmark workouts in experienced crossfitters

Abstract

Understanding crossfitters responses to daily loads is a challenge in prescribing various CrossFit® workouts. We aimed to evaluate and characterize the physiological and biomechanical aspects of the Fran and Isabel CrossFit®. Experiments comprises: (i) the Fran CrossFit® workout (three rounds of 21, 15 and 9 front squats to overhead press plus pull-up repetitions), performed intermittently and unbroken to evaluate physiological responses and post-workout recovery; and (ii) the Isabel workout (30 snatch repetitions with 61 kg), performed at extreme intensity to characterize oxygen uptake (V̇O2) kinetics, energy systems contributions, total energy expenditure and biomechanical changes, particularly in relation to relevant angles. Cardiorespiratory and metabolic variables were evaluated at baseline, during and post-workouts, while muscular functions were assessed at baseline and during the recovery period. The bioenergetic profile was evaluated by considering the sum of aerobic, anaerobic lactic and anaerobic alactic contributions. 3D markerless motion capture was used to collect data along the Isabel workout. The amplitude of the fast component V̇O2 was higher in the Isabel workout compared with unbroken Fran workout (42.0 vs 35.8 mL∙kg-1·min-1), contrary to the time constant (14.2 vs 23.7 s) whose mean values were higher in the unbroken Fran workout, with no differences in the time delay (4.3 vs 4.7 s, respectively) between the two workouts. The unbroken Fran workout elicited a higher peak V̇O2, heart rate, and aerobic contribution (62 vs 40 vs 41%) compared to Isabel and intermittent Fran workouts, which exhibited a higher anaerobic contribution (38 vs 60 vs 59%, respectively). Reduction in muscle function in jumping ability and plank prone test was observed in the recovery period from Fran workouts (intermittent and unbroken). At extreme Isabel workout intensity, maximal lift velocity and maximal lift power decreased from the initial to final phases, while the time from lift until the bar crossed the hip and shoulder decreased progressively along the workout. It is apparent that mechanical, intensity and volume differences between workout modes performed at maximal effort influence cardiorespiratory and bioenergetic profiles. This analysis provided new insights into selecting the prescription of intensity and recovery for CrossFit® workouts (and strength training) performed at maximal effort.