Exercise Intensity Thresholds: Identifying the Boundaries of Sustainable Performance

The [HHbMb] breakpoint during ramp exercise is suggested to resemble an upper limit of fractional oxygen extraction in the exercising leg muscles during incremental exercise and approximates VT2, maximal lactate steady state and critical power.

“For instance, the [HHbMb] breakpoint during ramp exercise is suggested to resemble an upper limit of fractional oxygen extraction in the exercising leg muscles during incremental exercise [9–11] and approximates VT2 [10,12,11,13–15], maximal lactate steady state [14,16] and critical power [14].”

HHb-BP has been associated with physiological thresholds, especially indicators of maximal metabolic steady state that delineate heavy and severe exercise domains.

“This plateau-like response has been associated with other physiological thresholds, especially those considered indicators of the maximal metabolic steady state, which delineate heavy and severe exercise domains (Bellotti et al. 2013; Keir et al. 2015, Turnes et al. 2019; Possamai et al. 2023).”

SmO2 at the vastus lateralis typically desaturates as a function of increasing exercise intensity during incremental cycling exercise, generally following a sigmoidal or segmented linear profile.

“During incremental cycling exercise, SmO2 measured at the vastus lateralis (VL) typically desaturates as a function of increasing exercise intensity, generally following a sigmoidal or segmented linear profile (16–20).”

Multiple studies have validated various stationary NIRS sensors with physiological and performance markers during various modes of exercise.

“Multiple studies have validated various stationary NIRS sensors with each of the physiological and performance markers outlined above, during various modes of exercise (12, 17, 22, 29–31).”