Assessment of body composition in heart transplant patients.

Orthotopic heart transplantation (OHT) recipients often experience increased body weight (BW) following surgery. Using hydrostatic weighing (HW), this study assessed the body density (BD) and body composition of 17 white and seven black male OHT patients. It examined the cross-validity of the Jackson and Pollock seven and three site skinfold (SF) regression equations for predicting BD in these patients. We hypothesized that both prednisone (P) dose and months post-operative (MPO) would be inversely related to BD. The average of the last five of ten HW trials was used in computing BD. BW and % body fat (BF) were 88.5 +/- 17.8 kg (mean +/- SD) and 33.5 +/- 9.4%, respectively. The correlation coefficient between hydrostatically determined BD and BD determined via two of the three intercept revised Jackson and Pollock SF equations was r = 0.89, SE = 0.009. A polynomial regression model for BD using P dose and MPO provided a correlation coefficient of r = 0.71, SE = 0.015. Partial correlation techniques incorporating SF, age, MPO, and P dose indicated that neither P dose or MPO provided any significant additive effect, above SF and age, when predicting BD. We conclude that in OHT patients receiving glucocorticoids, the intercept revised Jackson and Pollock SF regression equations are generally applicable and associated with a SE of +/- 4 BF percentage points. Up to 49 months after OHT, both P dose and MPO are inversely related to BD but provide no additive value above SF for predicting BD.

Physiological differences between black and white runners during a treadmill marathon.

To determine why black distance runners currently out-perform white distance runners in South Africa, we measured maximum oxygen consumption (VO2max), maximum workload during a VO2max test (Lmax), ventilation threshold (VThr), running economy, inspiratory ventilation (VI), tidal volume (VT), breathing frequency (f) and respiratory exchange ratio (RER) in sub-elite black and white runners matched for best standard 42.2 km marathon times. During maximal treadmill testing, the black runners achieved a significantly lower (P less than 0.05) Lmax (17 km h-1, 2% grade, vs 17 km h-1, 4% grade) and VI max (6.21 vs 6.82 l kg-2/3 min-1), which was the result of a lower VT (101 vs 119 ml kg-2/3 breath-1) as fmax was the same in both groups. The lower VT in the black runners was probably due to their smaller body size. The VThr occurred at a higher percentage VO2max in black than in white runners (82.7%, SD 7.7% vs 75.6%, SD 6.2% respectively) but there were no differences in the VO2max. However, during a 42.2-km marathon run on a treadmill, the black athletes ran at the higher percentage VO2max (76%, SD 7.9% vs 68%, SD 5.3%), RER (0.96, SD 0.07 vs 0.91, SD 0.04) and f (56 breaths min-1, SD 11 vs 47 breaths min-1, SD 10), and at lower VT (78 ml kg-2/3 breath-1, SD 15 vs 85 ml kg-2/3 breath-1, SD 19). The combination of higher f and lower VT resulted in an identical VI.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo approximations of the classic in vitro length-tension relationship: an isokinetic evaluation.

Several biarticular muscles of the human lower extremity were placed in various positions of stretch, using a hinged board to alter trunk-thigh relationships in 59 young adult volunteers of both sexes. Prior measurement, by direct x-ray of one subject on the test apparatus and by use of an articulated skeleton placed in the same pelvofemoral orientations as seen on the x-rays, supports the conclusion that the test positions of these 59 subjects were such that the biarticular extensor (rectus femoris) and flexors, (biceps femoris, semimembranosus and semitendinosus) were in fact being shortened or lengthened as desired under the prescribed positioning protocol. Isokinetic torques, total work output,; and average power production were obtained for maximal knee extensions and flexions through the full anatomical range of motion. The results support an assertion of close in vivo approximation to the classic in vitro length-tension relationship. J Orthop Sports Phys Ther 1986;7(5):222-231.

A comparison of 'anaerobic' components of O2 debt and the Wingate test.

This study compared measurements which were considered traditionally to reflect alactacid and lactacid components of anaerobic metabolism. Subjects (men (N = 9) and women (N = 5)) on one occasion performed an exhaustive cycle ergometer ride at VO2 max and had peak lactate and O2 debt (fast and slow components) determined. On a second occasion, they performed a Wingate test. All data were normalized for body weight. Very few correlations were found between O2 debt or peak lactate and the peak power, mean power and power decrease of the Wingate test. In particular, both peak lactate and the fast O2 debt component had low, nonsignificant correlations with either peak or mean power. The study failed to support the traditional assumptions that both tests are quantifying the same anaerobic energy systems.