Effects of a 6-week additional work on performance capacity: Hints for a parasympathic overtraining?

Introduction. Maximum performance can only be achieved with an optimal balance of training and recovery. Already 15 years ago Jeukendrup & Hesselink (1994) mentioned that hints can be derived from lactate curves concerning a potential overreaching. In this small study we show the effects of a six-week standard infantry military training on performance capacity in young elite orienteers. The potentially induced overreaching and the ingoing alterations of heart rate patterns and lactate answers shall be analysed. Material & Methods. Five young elite orienteers (22.6 ± 0.52 years / 178.4 ± 7.6 cm / 66.4 ± 3.4 kg) completed an exhaustive treadmill test, first at one and a half year before, second at half a year before and third immediately after completing a six-week period of a session of a hard infantry military training. Results. After the six-week additional military training measurements of heart rate decreased at speed 10.8 km/h from 142.6 ± 11.6 to 129.2 ± 11.9 (p = .0192); at speed 12.6 km/h from 153.4 ± 11.4 to 141.2 ± 12.6 (p = .0192); at speed 14.4 km/h from 166.4 ± 10 to 155.4 ± 12.2 (p = .02); at speed 16.2 km/h from 177.4 ± 6.9 to 168.4 ± 6.5 (p = .0244); at speed 18 km/h from 186.2 ± 5.8 to 181.4 ± 3.6 (p = .0313) compared to the measurement half a year earlier. Discussion. We strongly believe that these lower average heart rates for submaximal speed stages cannot be assessed as positive in terms of performance but might be in accordance with a parasympathetic overreaching respectively parasympathetic stimulation. The increased parasympathetic tone probably required a correspondingly stronger sympathetic stimulus for activation, which, however, could not act as efficiently as after normal training conditions as athletes were not rested well yielding to a shift of the heart rate/performance curve in line with findings of Jeukendrup & Hesselink (1994) of lactate curve in cyclists already 15 years ago.