Bestimmung des Intensitätsübergangs zwischen der „Heavy-„ und der „Severe-Domain“ bei Freizeit-Triathleten und -Radfahrern

Objective

Studies have proven the potential of the calculated maximal lactate steady-state (cMLSS) as a practical and time-efficient way to determine MLSS. Purpose of this study was to compare traditional approaches to distinguish the heavy from the severe exercise intensity domain with the cMLSS to evaluate its potential for physiological threshold determination.

Methods

Fifteen triathletes (3 women, 12 men; age: 37.63±11.47yr, bodyweight: 77.1±8.9kg, height: 178.5±8.1cm, maximum oxygen consumption [V˙O2MAX]: 52.6±5.9ml·min-1·kg-1) performed an isokinetic sprint of 15s to determine maximal glycolytic rate (vLaMAX) followed by an incremental test with assessment of gas exchange to determine V˙O2MAX and second ventilatory threshold (VT2). The calculation of cMLSS was conducted using V˙O2MAX and vLaMAX. Reverse lactate test (RLT) was performed on a separate day and the protocol (priming stages, one stage at estimated 105% of MLSS and reverse segments) was accompanied by blood lactate samples. Power at experimental thresholds (VT2, RLT) and cMLSS was compared using statistical methods for assessing agreement.

Results

Cycling power ±SD for RLT, cMLSS and VT2 was assessed at 236±34W, 229±38W and 250±36W. Intraclass correlation coefficients (ICC3,1) ranged from good (RLT vs. cMLSS: ICC3,1=0.806) to moderate (VT2 vs. cMLSS: ICC3,1=0.699). However, there were significant differences for VT2 vs. cMLSS (p=0.012, d=0.740), but not for RLT vs. cMLSS (p=0.268, d=0.310).

Conclusion

The results accord to published comparisons of threshold concepts, also showing large individual differences. The observed deviations could originate from the methodological procedure, but are most likely attributable to divergent underlying physiological mechanisms of respiratory and metabolic responses during exercise. The cMLSS includes more information about the interaction of endurance performance determinants (V˙O2MAX, vLaMAX) and could give more goal-oriented training recommendations.

■ Siemers P, Schaffarczyk M, Gronwald T