Cardiovascular Health and Exercise

Lipid Lipoprotein Profiles

Abnormal lipid lipoprotein profiles have been associated with an increased risk for CVD (Hurley & 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 & Wells 1989; Solomonow et al. 1997; Nash et al. 2001; de Groot et al. 2003; Stewart et al. 2004; El-Sayed & Younesian 2005) (Table 13).

Author, Year;

Country

Score

Research Design

Sample Size
Methods
Outcomes
de Groot et al., 2003; Netherlands

PEDro = 7

RCT

Level 1

N = 6

 Population: 4 male, 2 female, C5-L1, AIS A (n = 1), B (n = 1), and C (n = 4), age 36 yrs, 116 d post-injury.

Treatment: Randomized to low-intensity (50%–60% HRR) or high-intensity (70%–80% HRR) arm ergometry; 20 min/d, 3 d/wk, 8 wks.

Outcome Measures: lipid profiles including total cholesterol (TC), HDL, LDL, triglycerides (TG).

 1.The TC/HDL ratio and triglycerides decreased significantly more in the high-intensity group.
Hooker & Wells 1989; USA

Prospective controlled trial

Level 2

N = 8

 Population: Low-intensity group: n = 6, 3 male, 3 female, C5-T10, age 26–36 yrs, 3 months to 19 yrs post-injury; moderate-intensity group: n = 5, 3 male, 2 female, C5-T9, age 23–30 yrs, 2–19 yrs post-injury.

Treatment: Wheelchair ergometry 20 min/d, 3 d/wk, 8 wks: low-intensity (50%–60% max HRR) and moderate intensity (70%–80% max HRR).

Outcome Measures: total cholesterol (TC), triglycerides, HDL, LDL.

 1. No change in lipid levels in low-intensity group.

2. Significant increases in HDL and decreases in triglycerides, LDL, and the TC/HDL ratio in the moderate intensity group.
El-Sayed et al., 2005;UK

Pre-post

Level 4

N = 12

 Population: 5 SCI, lesion below T10, age 32 yrs; 7 AB controls, age 31 yrs.

Treatment: Arm ergometry, 30 min/d (60%–65%VO2peak), 3 d/wk, 12 wks.

Outcome Measures: VO2peak, peak HR, peak workload, total cholesterol (TC), triglycerides, HDL.

 1. Training improved HDL but did not alter TC or triglycerides.
Stewart et al., 2004; Canada

Pre-post

Level 4

N = 9

 Population: 8 male, 1 female, incomplete AIS C, C4-T12, 8.1 yrs post-injury.

Treatment: Body-weight–supported treadmill training, 3 d/wk, 6 months.

Outcome Measures: ambulatory capacity (Wernig Walking Scale), cholesterol, HDL, LDL, triglycerides.

 1. There were significant reductions in TC (-11.2%), LDL (-12.9%), and TC/HDL (-19.8%).
Nash et al., 2001; USA

Pre-post

Level 4

N=5

 Population: 5 males, complete lesions T6-L1, age 37.8 yrs, 4.8 yrs post-injury.

Treatment: Circuit resistance training (50%–60%1 repetition maximum), 3 d/wk, 12 wks.

Outcome Measures: VO2peak, time to fatigue, TC, triglycerides, HDL, LDL.

 1. There were significant decreases in LDL, LDL/HDL, and TC/HDL after training.
Solomonow et al., 1997; USA

Pre-post

Level 4

N = 70/33

 Population: All participants had paraplegia, no other details given.

Treatment: Reciprocating gait orthosis powered with electrical muscle stimulation, 3 hr/wk, 14 wks.

Outcome Measures: cholesterol, LDL, HDL

 1. There were significant reductions in total cholesterol, LDL, LDL/HDL ratio, and TC/HDL ratio in 8 patients with initially high total cholesterol levels (>200 mg·dL-1).

Discussion

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 & Wells 1989), and several level 4 studies (Solomonow et al. 1997; Nash et al. 2001; Stewart et al. 2004; El-Sayed & 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.

Conclusion

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.

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