Abnormal lipid lipoprotein profiles have been associated with an increased risk for CVD (Hurley and Hagberg 1998, Warburton et al. 2001b, 2001a, Warburton et al. 2006). Several studies have revealed worsened lipid lipoprotein profiles in persons with SCI (Brenes et al. 1986, Dearwater et al. 1986, Bauman et al. 1992a, Krum et al. 1992, Maki et al. 1995, Dallmeijer et al. 1997). Routine physical activity has been shown to enhance lipid lipoprotein profiles by reducing triglycerides (TG), increasing HDL, and lowering LDL/HDL in the general population (Warburton et al. 2001a, 2001b, Warburton et al. 2006). Although limited, similar findings have been observed in persons with SCI (Hooker and Wells 1989, Solomonow et al. 1997, Nash et al. 2001, de Groot et al. 2003, Stewart et al. 2004, El-Sayed and Younesian 2005) (Table 13). Table 12 describes the common lipid lipoprotein measurements.
The information regarding the effects of exercise training on lipid lipoprotein profile is derived from one high-quality RCT (level 1b) (de Groot et al. 2003), one nonrandomized, prospective controlled trial (level 2) (Hooker and Wells 1989), and several level 4 studies (Solomonow et al. 1997, Nash et al. 2001, Stewart et al. 2004, El-Sayed and Younesian 2005) (N = 110). The majority of the investigations examined a form of aerobic training (either arm ergometry or assisted treadmill walking). Another investigation examined the effects of reciprocating gait orthosis powered with electrical muscle stimulation.
These findings provide level 1b evidence (based on one high-quality RCT and several lower quality studies) for the role of exercise in the reduction of atherogenic lipid lipoprotein profiles and the reduction of the risk for CVD in persons with SCI. It appears that a minimal threshold of training exists for changes in lipoprotein profile. Authors have reported that 70% of maximal HR reserve (for at least 20 min/day, three days/week for eight weeks) is the threshold necessary to achieve significant improvements in lipid lipoprotein profiles. Future research is warranted, however, to quantify the effects of varying forms of exercise (including aerobic exercise, resistance exercise, and FES) on lipid lipoprotein profiles in persons with SCI.
There is level 1b evidence from 1 high quality RCT (de Groot et al. 2003) to suggest that aerobic exercise training programs (performed at a moderate to vigorous intensity 20-30 min/day, 3 days per week for 8 weeks) are effective in improving the lipid lipoprotein profiles of persons with SCI.
Preliminary evidence (level 4; Solomonow et al. 1997) also indicates that the use of a reciprocating gait orthosis with FES training (3 hours/week, for 14 weeks) may improve lipid lipoprotein profiles in SCI.
- Aerobic and FES exercise training may lead to improvements in lipid lipoprotein profile that are clinically relevant for the at risk SCI population. The optimal training program for changes in lipid lipoprotein profile remains to be determined. However, a minimal aerobic exercise intensity of 70% of heart rate reserve on most days of the week appears to be a good general recommendation for improving lipid lipoprotein profile in persons with SCI.