This project examined associations between physiological parameters and performance during different efforts in handcycling. Athletes performed a 30-second Wingate, a maximal incremental test and a 20-minute time-trial (TT) on an arm ergometer, during which muscle oxygenation of the biceps brachii (BB), triceps brachii (TB), anterior deltoid (AD), and extensor carpi radialis brevis (ER) was measured using near-infrared spectroscopy (NIRS, Moxy monitors). Oxygen consumption (VO2), cardiac output and power were also evaluated, and grip strength was assessed bilaterally. Pearson and Spearman correlations revealed that VO2max (R = 0.90 [0.08, 1.91], p = 0.040) and BB O2 extraction (R = 0.86 [0.16, 1.57], p = 0.027) were associated to maximal aerobic power (MAP). AD O2 extraction (R = 1.0, p < 0.001), reoxygenation of TB (R = 0.82 [-0.15, 0.99], p = 0.046), AD (R = 0.92 [0.17, 1.57], p = 0.029) and ER (R = 0.83 [-0.13, 0.99], p = 0.042), deoxygenation of AD (R = -0.90 [-1.00, 0.17], p = 0.037) and ER (R = -0.87 [-1.56, -0.18], p = 0.025) were associated to Wingate mean power. Maximal deoxygenation for the muscles average (R = -0.88 [-1.76, 0.01], p = 0.049), deoxygenation rate of AD (R = -1.00 [-0.83, 0.63], p < 0.001), BB (R = -0.95 [-1.36, 0.03], p = 0.036), and ER (-0.90 [-1.00, 0.17], p = 0.037), were associated to TT mean power. Reoxygenation rate of AD (R = 0.97 [0.18, 1.51], p = 0.032) and BB (-0.99 [-0.98, 0.30], p = 0.015) were associated to mean power and TT distance, respectively. Analysis of variance revealed that maximal ER O2 extraction in the incremental test was 37% higher than in the Wingate, and ER deoxygenation in the Wingate was 88% faster than in the TT. For the physiological variables examined during the TT, most of the time was spent in the highest intensity zone (above 2nd lactate threshold) as compared to the lower intensity zones. Results demonstrate the contribution of peripheral adaptations to predict handcycling performance and suggest that upper body muscles oxygenation capacity should be considered in their training regime.