A Long-term Longitudinal Survey Of The Training Effects On Cardiorespiratory System In Paraplegics

Abstract

Cardiovascular risk is higher in spinal cord injured (SCI) patients than in able-bodied people, mainly due to physical inactivity. Sedentary lifestyle can lead to the "hypokinetic syndrome", characterized by progressive loss of functional muscular mass and cardiovascular fitness. In particular, left ventricle "electrical predominance" is not evident in sedentary SCI patients, whose ECG is often characterized by a right shift of cardiac electric axis. PURPOSE: To evaluate the effects of long term regular aerobic sport practice on cardiac response to exercise, ventilatory function and ECG in SCI patients. METHODS: Six SCI patients (lesion level T1-T10; age 34.6±2.8 yrs [m±SD], lesion duration 15.7±8.2 yrs) participated in the study. All the subjects were aerobically trained twice a week for two hours. Body weight (BW), ventilatory parameters (FVC, Forced Vital Capacity, FEV1, Forced Expiratory Volume in 1 Second) and ECG parameters (PQ, QT, electrical axis, heart rate [HR]) were monitored for 10 years, in occasion of yearly medical controls. All the patients were evaluated on a wheelchair ergometer, by means of an incremental maximal exercise test. ECG was recorded at rest (HRrest), during the last minute of the maximal speed achieved (HRmax) and during recovery (1½ minute from exercise stop [HRrec]). RESULTS: BW monotonically increased through the observation period, from 61.1±8.0 Kg to 69.7±14.4Kg (p<0.05, year 1 vs year 10). CV and FEV1 decreased from 3.6±0.7 to 3.0±1.2 l and from 3.1±0.8 to 2.4±1.1 l, respectively (p<0.05). Achieved maximal speeds decreased from 7.2±1.0 to 5.9±0.8 Km.h-1 (p=ns). Although not significantly, HRmax increased from 110±20 to 135±20 bpm, whereas HRrest and HRrec did not change. QT and PQ showed no changes throughout the observation period. Mean electric axis progressively shifted leftwards, from 68° to 43° (p<0.05). CONCLUSIONS: Our results suggest an important role for physical activity in the cardio-respiratory reconditioning of SCI patients. Although in these patients BW, respiratory function and HR were not affected by long term aerobic training, myocardium positively adapted to chronic exercise, presumably by an increase of left ventricular mass. Thus, physical exercise may slow down the progressive deterioration of cardiovascular function in paraplegics.