Abstract Measuring and monitoring individual cardiorespiratory fitness through a valid and accessible non‐exhaustive surrogate is required. Techniques measuring haemodynamics have shown promise, and this study aimed to optimize the predictive validity of these approaches alongside developing predictive equations. In a two‐study design, 8 (pilot study) and 30 (confirmation study) healthy adults completed exercise testing to assess maximal oxygen consumption () and an ischaemic occlusion test on the upper thigh to assess superficial femoral blood flow from ultrasonography and skeletal muscle oxygenation (SmO 2 ) by near‐infrared spectroscopy (NIRS) before, during and post‐cuff release. In study 1, treadmill running and a 5‐min 220 mmHg ischaemic cuff pressure were performed, whereas in study 2, cycling ergometry and a 3‐min 300 mmHg cuff pressure were applied. In study 1 and study 2, abs and rel were correlated to peak blood flow post‐cuff occlusion ( r = 0.57–0.84, all P < 0.01). In study 2, several NIRS based metrics of post‐occlusive reactive hyperaemia were strongly correlated with abs and rel (all P < 0.001). Moreover, the magnitude of oxygen desaturation during the cuff occlusion was highly significantly related to both abs and rel (all P < 0.001). As an example, the SmO 2 desaturation slope was strongly associated with abs ( r = −0.74, P < 0.001). Finally, intercorrelations between the rate of SmO 2 desaturation during cuff occlusion and the rate of SmO 2 reoxygenation and peak skeletal muscle blood flow post‐cuff occlusion were observed ( P < 0.01). An ischaemic‐based test of skeletal muscle haemodynamic profiles could potentially be used to predict and estimate a person's fitness.
Lesmana et al. (Fri,) studied this question.