Effects of low- and moderate-intensity training in spinal cord-injured persons

This study examined the applicability of exercise prescription guidelines established for the able-bodied to spinal cord-injured (SCI) persons. Two SCI groups performed wheelchair ergometry (WCE) 20 min three times per week for 8 wk. Low-intensity (LI, N=6) and moderate-intensity (MI, N=5) groups trained at 50-60% and 70-80% maximal heart rate reserve (HRR), respectively. The subjects completed an incremental discontinuous maximal WCE test to exhaustion pre- and post-training. A submaximal WCE test consisting of 4-min exercise stages at power outputs of 5, 10, and 15 W was also performed pre- and post-training. Blood samples were collected before and after training and analyzed for total cholesterol (TC), triglycerides (TG), high-density lipoprotein-cholesterol (HDL-C), and low-density lipoprotein-cholesterol (LDL-C). The TC/HDL-C ratio was calculated. Both groups exhibited no significant changes (P > 0.10) in VO_2max, HR_max, PO_max, lactate (La)_max, and VO₂ at 4 mmol [La]. No pre- to post-training differences were recorded in the LI group for submaximal VO₂, HR, V_E, La, and ratings of perceived exertion (RPE). The MI group had significantly lower (P < 0.10) post-training submaximal HR, La, and RPE and no changes in VO₂ or V_E. Blood lipid levels remained unaltered in the LI group, while the MI group exhibited significant increases in HDL-C and decreases in TG, LDL-C, and the TC/HDL-C ratio. The maximal test data revealed that 8 wk of LI and MI wheelchair ergometry training did not improve VO_2max in SCI persons. The submaximal test and blood lipid results indicate that 70% maximal HRR was the threshold intensity needed to elicit training benefits in SCI persons.