Does cumulating endurance training at the weekends impair training effectiveness?

Due to occupational restrictions many people's recreational endurance activities are confined to the weekends. We intended to clarify if cumulating the training load in such a way diminishes endurance gains. We conducted a longitudinal study comparing training-induced changes within three independent samples. Thirty-eight healthy untrained participants (45 ± 8 years, 80 ± 18kg; 172 ± 9cm) were stratified for endurance capacity and sex and randomly assigned to three groups: 'weekend warrior' (n = 13, two sessions per week on consecutive days, 75min each, intensity 90% of the anaerobic threshold; baseline lactate + 1.5 mmol/l), regular training (n = 12, five sessions per week, 30min each, same intensity as weekend warrior), and control (n = 13, no training). Training was conducted over 12 weeks and monitored by means of heart rate. Identical graded treadmill protocols before and after the training program served for exercise prescription and assessment of endurance effects. Results VO2max improved similarly in weekend warrior (+ 3.4ml/min per kg) and register training (+ 1.5ml/min per kg; P =0.20 between groups). Compared with controls (− 1.0ml/min per kg) this effect was significant for weekend warriors (P<0.01) whereas there was only a tendency for the regular training group (P =0.10). In comparison with controls (mean decrease, 3 beats/min), the average heart rate during exercise decreased significantly by 11 beats/min (weekend warriors, P<0.01) and 9 beats/min (regular training, P<0.05). There was no significant difference, however, between the weekend warrior and regular training groups (P =0.99). In a middle-aged population of healthy untrained subjects, cumulating the training load at the weekends does not lead to an impairment of endurance gains in comparison with a smoother training distribution.