[Maximal physiological response during exertion in quadriplegic subjects]

Comparison of Peak Oxygen Uptake Between Upper-Body Exercise Modes: A Systematic Literature Review and Meta-Analysis

Purpose: To compare peak oxygen uptake (VO_2peak) between the asynchronous arm crank ergometry (ACE), and synchronous wheelchair ergometry (WERG), wheelchair treadmill (WTR), and upper-body poling (UBP) mode.

Methods: PubMed, Scopus, CINAHL, and SPORTDiscus™ were systematically searched, and identified studies screened based on title, abstract, and thereafter full-text. Studies comparing VO_2peak between ≥2 of the modes were included. A meta-analysis was performed by pooling the differences in VO_2peak between upper-body exercise modes. The quality of the included studies was assessed and the level of evidence (LoE) established for each mode comparison. Meta-regression analyses investigated the effect of total body mass and participant-related characteristics (% of able-bodied participants, % of participants with tetraplegia and % of participants who are wheelchair athletes) on differences in VO_2peak between modes.

Results: Of the 19 studies included in this review, 14 studies investigated the difference in absolute and body-mass normalized VO_2peak between ACE and WERG, and 5 studies examined the differences between ACE and WTR. No significant difference in absolute or body-mass normalized VO_2peak was found between ACE and WERG (overall effect ±95% CI: 0.01 ± 0.06 L·min⁻¹ and 0.06 ± 1.2 ml·kg⁻¹·min⁻¹, both p > 0.75; LoE: strong). No significant difference in absolute or body-mass normalized VO_2peak was found between ACE and WTR (overall effect ±95% CI: −0.10 ± 0.18 L·min⁻¹ and −1.8 ± 2.5 ml·kg⁻¹·min⁻¹, both p > 0.14; LoE: moderate). Absolute and/or body-mass normalized VO_2peak did not differ between WERG and WTR in one study with 13 participants (LoE: limited) and between ACE and UBP in one study with 18 participants (LoE: moderate). In the meta-regression analyses, there was no significant effect of the investigated factors on differences in VO_2peak.

Conclusions: The differences between the asynchronous ACE and synchronous WERG propulsion, including possible differences in trunk involvement, do not seem to influence VO_2peak. Therefore, ACE and WERG can be used interchangeably to test VO_2peak. Possible differences in VO_2peak in all other mode comparisons remain unclear due to the wide CIs and limited to moderate LoE.

A new conceptual framework for the integrated neural control of locomotor and sympathetic function: implications for exercise after spinal cord injury

All mammals, including humans, are designed to produce sustained locomotor movements. Many higher centres are involved in movement, but ultimately these centres act upon a core "rhythm-generating" network within the brainstem-spinal cord. In addition, endurance-based locomotor exercise requires sympathetic neural support to maintain homeostasis and to provide needed metabolic resources. This review focuses on the roles and integration of these 2 neural systems. Part I reviews the cardiovascular, thermoregulatory, and metabolic functions under spinal sympathetic control as revealed by spinal cord injury at different levels. Part II examines the integration between brainstem-spinal sympathetic pathways and the neural circuitry producing motor rhythms. In particular, the rostroventral medulla (RVM) contains the neural circuitry that (i) integrates heart rate, contractility, and blood flow in response to postural changes; (ii) initiates and maintains cardiovascular adaptations for exercise; (iii) provides direct descending innervation to preganglionic neurons innervating the adrenal glands, white adipose tissue, and tissues responsible for cooling the body; (iv) integrates descending sympathetic drive for energy substrate mobilization (lipolysis); and (v) is the relay for descending locomotor commands arising from higher brain centres. A unifying conceptual framework is presented, in which the RVM serves as the final descending supraspinal "exercise integration centre" linking the descending locomotor command signal with the metabolic and homeostatic support needed to produce prolonged rhythmic activities. The role and rationale for an ascending sympathetic and locomotor drive from the lower to upper limbs within this framework is presented. Examples of new research directions based on this unifying framework are discussed.

Aerobic capacity and peak power output of elite quadriplegic games players

BACKGROUND

Participation in wheelchair sports such as tennis and rugby enables people with quadriplegia to compete both individually and as a team at the highest level. Both sports are dominated by frequent, intermittent, short term power demands superimposed on a background of aerobic activity.

OBJECTIVE

To gain physiological profiles of highly trained British quadriplegic athletes, and to examine the relation between aerobic and sprint capacity.

METHODS

Eight male quadriplegic athletes performed an arm crank exercise using an ergometer fitted with a Schoberer Rad Messtechnik (SRM) powermeter. The sprint test consisted of three maximum-effort sprints of five seconds duration against a resistance of 2%, 3%, and 4% of body mass. The highest power output obtained was recorded (PPO). Peak oxygen consumption (V(O2peak)), peak heart rate (HR(peak)), and maximal power output (PO(aer)) were determined.

RESULTS

Mean PO(aer) was 67.7 (16.2) W, mean V(O2peak) was 0.96 (0.17) litres/min, and HR(peak) was 134 (19) beats/min for the group. There was high variability among subjects. Peak power over the five second sprint for the group was 220 (62) W. There was a significant correlation between V(O2peak) (litres/min) and PO(aer) (W) (r = 0.74, p<0.05).

CONCLUSIONS

These British quadriplegic athletes have relatively high aerobic fitness when compared with the available literature. Moreover, the anaerobic capacity of these athletes appeared to be relatively high compared with paraplegic participants.

Physical capacity in wheelchair-dependent persons with a spinal cord injury: a critical review of the literature

STUDY DESIGN

Review of publications.

OBJECTIVE

To assess the level of physical capacity (peak oxygen uptake, peak power output, muscle strength of the upper extremity and respiratory function) in wheelchair-dependent persons with a spinal cord injury (SCI).

SETTING

Erasmus MC, University Medical Centre Rotterdam, The Netherlands.

METHODS

Pubmed (Medline) search of publications from 1980 onwards. Studies were systematically assessed. Weighted means were calculated for baseline values.

RESULTS

In tetraplegia, the weighted mean for peak oxygen uptake was 0.89 l/min for the wheelchair exercise test (WCE) and 0.87 l/min for arm-cranking or hand-cycling (ACE). The peak power output was 26 W (WCE) and 40 W (ACE). In paraplegia, the peak oxygen uptake was 2.10 l/min (WCE) and 1.51 l/min (ACE), whereas the peak power output was 74 W (ACE) and 85 W (WCE). In paraplegia, muscle strength of the upper extremity and respiratory function were comparable to that in the able-bodied population. In tetraplegia muscle strength varied greatly, and respiratory function was reduced to 55-59% of the predicted values for an age-, gender- and height-matched able-bodied population.

CONCLUSIONS

Physical capacity is reduced and varies in SCI. The variation between results is caused by population and methodological differences. Standardized measurement of physical capacity is needed to further develop comparative values for clinical practice and rehabilitation research.

Réentraînement a l'effort chez le blesse médullaire

INTRODUCTION

Individualised exercise training programs in spinal cord injury (SCI) individuals are considered highly effective for improving and maintaining capacity for physical activity, as well as for reducing cardiovascular risk. However, no consensus exists on the type, intensity, and frequency of the training programs for SCI.

OBJECTIVE

To review the literature about training program characteristics for SCI and describe their efficacy, limits, and results, with the aim of proposing specific recommendations.

METHODS

Query using Medline and Embase databases. Ninety-nine references were found, including the following: Clinical studies examining physical endurance capacity of individuals with SCI, physiological responses to maximal exercise, or cardiovascular differences between sedentary and wheelchair-trained subjects; Articles? investigating the effects of training programmes for SCI.

RESULTS

Various combinations of training intensity, duration, frequency, type, and ergometers have been proposed for SCI. Whatever the characteristics of the training program, a review of 25 cardiorespiratory training studies involving SCI subjects revealed an average improvement of 9% to 99% in VO2max, 19% to 118% in power output, and a decrease in submaximal values after 4 to 36 weeks of training.

DISCUSSION - CONCLUSION

Wheelchair ergometers seems to be interesting for SCI because it mimics closely the daily motor tasks of wheelchair users and allows for adjustment of the wheelchair. Both continuous and interval training programmes are appropriate, but intermittent exercise intensities may be more beneficial since they mimic the intermittent nature of daily activity patterns. Furthermore, on the basis of the results of these studies, we recommend that training at or above 70% of maximum heart rate, for 30 minutes of rhythmic exercise, three days per week during eight weeks, will provide a sound of basis for design of an endurance exercise programme for people with SCI.