The effects of a 6 weeks interval training with a wheelchair ergometer on the power and endurance of the upper limbs (UL) were studied in ten young able-bodied males. All subjects performed a maximal progressive test (10 W/2 min) on a wheelchair ergometer to measure the ventilation (VE), respiratory exchanges (VO2, VCO2) and oxygen pulse (O2p) at the maximal tolerated power (MTP) and ventilatory threshold (VT). Endurance capacity was measured with the tailored 45 min Square Wave Endurance Exercise Test (SWEET) from MTP and VT. Arm and forearm perimeters, diameters and skinfold thickness were also measured. The subjects were divided into a control group (CG n = 5) and a training group (TG n = 5; 3 SWEET sessions/week/6-week) with matched physical characteristics. Training the UL resulted in significant increases of parameters at MTP (power + 63%, peak VO2 + 33%, O2 pulse + 25%) and at VT (power + 125%, VO2 + 48%, O2 pulse + 33%). The UL diameter and perimeter significantly increased, and the skinfold thickness decreased. None of these variables showed a significant change in the CG. We conclude that this training improves specific force and endurance of the UL, by acting centrally as reflected by oxygen pulse increase, as well as peripherally as shown by morphologic changes.