RELATIONSHIP BETWEEN MAXIMAL OXYGEN-UPTAKE ON DIFFERENT ERGOMETERS, LEAN ARM VOLUME AND STRENGTH IN PARAPLEGIC SUBJECTS

The present experiment was designed to study the importance of strengt h and muscle mass as factors limiting maximal oxygen uptake (VO2max) i n wheelchair subjects. Thirteen paraplegic subjects [mean age 29.8 (8. 7) years] were studied during continuous incremental exercises until e xhaustion on an arm-cranking ergometer (AC)I a wheelchair ergometer (W E) and motor-driven treadmill(TM). Lean arm volume (LAV) was estimated using an anthropometric method based upon the measurement of various circumferences of the arm and forearm. Maximal strength (MVF) was meas ured while pushing on the rim of the wheelchair for three positions of the hand on the rim (-30 degrees, 0 degrees and +30 degrees). The res ults indicate that paraplegic subjects reached a similar VO2max [1.23 (0.34) l . min(-1), 1.25 (0.38) l.min(-1) for AC. TM and WE, respectiv ely] and VO2max/body mass [19.7 (5.2) ml.min(-1).kg(-1), 19.5 (6.14) m l.min(-1).kg(-1), 19.18 (4.27) ml.min(-1).kg(-1) for AC. TM and WE, re spectively on the three ergometers. Maximal heart rate f(cmax) during the last minute of AC (173 (17) beats.min(-1)], TM [168 (14) beats.min (-1)], and WE [165 (16) beats.min(-1)], were correlated, but f(cmax) w as significantly higher for AC than for TM (P < 0.03). There were sign ificant correlations between MVF and LAV (P < 0.001) and between the M VF data obtained at different angles of the hand on the rim [311.9 (90 .1) N. 313.2 (81.2) N, 257.1 (71) N, at -30 degrees, 0 degrees and +30 degrees, respectively]. There was no correlation between f(cmax) and LAV or MVF. The relatively low values of VO2max; suggest that VO2max w as, at least in part, limited by local aerobic factors instead of cent ral cardiovascular factors. On the other hand, the lack of a significa nt correlation between VO2max and MVF or muscle mass was not in favour of muscle strength being the main factor limiting VO2max in our subje cts.