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To examine the effect of cold-water immersion at different depths on thermal and metabolic responses, eight men (25 yr old, 16% body fat) attempted 12 tests: immersed to the knee (K), hip (H), and shoulder (Sh) in 15 and 25 degrees C water during both rest (R) or leg cycling [35% peak oxygen uptake; (E)] for up to 135 min. At 15 degrees C, rectal (Tre) and esophageal temperatures (Tes) between R and E were not different in Sh and H groups (P > 0.05), whereas both in K group were higher during E than R (P < 0.05). At 25 degrees C, Tre was higher (P < 0.05) during E than R at all depths, whereas Tes during E was higher than during R in H and K groups. Tre remained at control levels in K-E at 15 degrees C, K-E at 25 degrees C, and in H-E groups at 25 degrees C, whereas Tes remained unchanged in K-E at 15 degrees C, in K-R at 15 degrees C, and in all 25 degrees C conditions (P > 0.05). During R and E, the magnitude of Tre change was greater (P < 0.05) than the magnitude of Tes change in Sh and H groups, whereas it was not different in the K group (P > 0.05). Total heat flow was progressive with water depth. During R at 15 and 25 degrees C, heat production was not increased in K and H groups from control level (P > 0.05) but it did increase in Sh group (P < 0.05). The increase in heat production during E compared with R was smaller (P < 0.05) in Sh (121 +/- 7 W/m2 at 15 degrees C and 97 +/- 6 W/m2 at 25 degrees C) than in H (156 +/- 6 and 126 +/- 5 W/m2, respectively) and K groups (155 +/- 4 and 165 +/- 6 W/m2, respectively). These data suggest that Tre and Tes respond differently during partial cold-water immersion. In addition, water levels above knee in 15 degrees C and above hip in 25 degrees C cause depression of internal temperatures mainly due to insufficient heat production offsetting heat loss even during light exercise.

The influence of exercise intensity on thermoregulation was studied in 8 men and 8 women volunteers during three levels of arm-leg exercise (level I: 700 ml oxygen (O2).min-1; level II: 1250 ml O2.min-1; level III: 1700 ml O2.min-1) for 1 h in water at 20 and 28 degrees C (Tw). For the men in Tw 28 degrees C the rectal temperature (Tre) fell 0.79 degree C (P less than 0.05) during immersion in both rest and level-I exercise. With level-II exercise a drop in Tre of 0.54 degree C (P less than 0.05) was noted, while at level-III exercise Tre did not change from the pre-immersion value. At Tw of 20 degrees C, Tre fell throughout immersion with no significant difference in final Tre observed between rest and any exercise level. For the women at rest at Tw 28 degrees C, Tre fell 0.80 degree C (P less than 0.05) below the pre-immersion value. With the two more intense levels of exercise Tre did not decrease during immersion. In Tw 20 degrees C, the women maintained higher Tre (P less than 0.05) during level-II and level-III exercise compared to rest and exercise at level I. The Tre responses were related to changes in tissue insulation (I(t)) between rest and exercise with the largest reductions in I(t) noted between rest and level-I exercise across Tw and gender. For mean and women of similar percentage body fat, decreases in Tre were greater for the women at rest and level-I exercise in Tw 20 degrees C (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The present study examined the hemodynamic differences between upper- and lower-body exercise where the total power output (PO) was proportionally distributed between the upper and lower body. Six males completed five combinations of arm-leg exercise at maximal and three submaximal intensities. The ratio of arm PO to total PO for each exercise combination was 0, 25, 50, 75, and 100%. At each submaximal intensity, VO2 and cardiac output (Q) were not different (P greater than 0.05) across exercise combinations. Likewise, heart rate (HR) responses were not different for 0, 25, 50, and 75% at level 1 (mean = 102, 102, 106, 106 beats.min-1, respectively), level 2 (mean = 114, 110, 119, 118 beats.min-1, respectively), and level 3 (mean = 127, 124, 132, 131 beats.min-1, respectively). However, HR for 100% (arm-only exercise) tended to be higher than 0% at level 1 (delta HR = 10 beats.min-1; P less than 0.10), level 2 (delta HR = 12 beats.min-1, P less than 0.06) and level 3 (delta HR = 10 beats.min-1; P less than 0.06). At level 1, stroke volume (SV) remained essentially unchanged from 0-75%, while SV at 100% (108 ml) was slightly though not significantly lower (P less than 0.10) than 0% (125 ml). At exercise levels 2 and 3, SV remained unchanged for 0 and 25%; however, SV at 50, 75, and 100% were generally lower (P less than 0.05) compared with 0%. These results indicate that involving the leg musculature to varying degrees during arm-leg exercise attenuates the hemodynamic differences observed during strict upper body versus strict lower body exercise.

In the present study, the effects of temporomandibular joint (TMJ) repositioning by use of an acrylic appliance on maximum and submaximum physiologic and performance measures were evaluated in seven male and four female volunteers with documented TMJ malalignment. In an attempt to remove design inadequacies of previous research in this area, a double-blind strategy was utilized. Subjects were randomly assigned to each of four conditions: 1) normal, without a bite splint, 2) with a placebo splint with no occlusal contact so as to maintain normal jaw position, 3) with a splint that optimized jaw position, and 4) with a splint that magnified the subjects normal degree of malocclusion. Measurements were taken of visual reaction time and movement time, muscular strength of the grip, elbow flexors, and leg extensors, submaximal and maximal oxygen uptake, perceived exertion, anaerobic power output, and all-out working capacity in both arm and leg exercise on a cycle ergometer. Analysis of variance for repeated measures indicated that in no instance were the differences in mean scores on physiologic and performance measures with TMJ repositioning or placebo statistically significant when compared with the normal condition. This was the case for the group as a whole or when the five subjects with the greatest TMJ dysfunction were analyzed separately. These findings strongly support the contention that the beneficial effects of short-term TMJ repositioning on exercise performance noted in previous reports may be the result of inadequacies in research design and evaluation rather than the true effects of the bite splint.

The specificity of aerobic training for upper-body exercise requiring differing amounts of muscle mass was evaluated in 25 college-aged male recreational swimmers who were randomly assigned to either a non-training control group (N = 9), a 10-wk swim(S)-training group (N = 9), or a group that trained with a standard swim-bench pulley system (SB; N = 7). For all subjects prior to training, tethered-swimming peak VO2 averaged 19% below treadmill values (P less than 0.01), while SB-ergometry peak VO2 was 50% and 39% below running and swimming values, respectively (P less than 0.01). Significant (P less than 0.01) increases of peak VO2 in tethered swimming (11%) and SB (21%) were observed for the SB-trained group, while the S-trained group improved (P less than 0.01) 18% and 19% on the tethered swimming and SB tests, respectively. No changes were observed during treadmill running, and the control subjects remained unchanged on all measures. Comparisons between training groups indicated that although both groups improved to a similar extent when measured on the swim bench, the 0.53 l X min-1 improvement in tethered-swimming peak VO2 for the S-trained group was greater (P less than 0.05) than the 0.32 l X min-1 increase noted for the SB-trained group. The comparisons between SB and S exercise vs treadmill exercise support the specificity of aerobic improvement with training and suggest that local adaptations contribute significantly to improvements in peak VO2. Furthermore, the present data indicate that SB exercise activates a considerable portion of the musculature involved in swimming, and that aerobic improvements with SB training are directly transferred to swimming.

Physiologic responses to ballet exercise and VO2max during treadmill running were studied in elite professional ballet dancers (7 men, 8 women; age 20-30 yr) from American Ballet Theatre. Ten dancer were studied during standard 1-h ballet classes consisting of 28 min of barre and 32 min of center floor exercise. Eight dancers performed maximal treadmill running tests yielding VO2max values (ml . min-1 . kg-1) of 48.2 (range 43.8-51.9) for men and 43.7 (range 40.9-50.1) for women. Mean VO2 (ml . min-1 . kg-1) during barre exercise was 18.5 (38% VO2max) for men and 16.5 (38% VO2max) for women; during center floor exercise 26.3 (55% VO2max) for men and 20.1 (46% VO2max) for women, with a peak of 77% VO2max for a male dancer. Mean caloric output values (kcal . kg-1 . min-1) during barre exercise were 0.09 and 0.08 for men and women, respectively, and during center floor exercise 0.13 for men and 0.10 for women, with a peak of 0.18 for one male dancer. Estimated net caloric outputs for the entire ballet class averaged 200 kcal . h-1 for women and 300 kcal . h-1 for men. During barre exercise, HR was below the training sensitive zone (70% HR max) for significant periods of time. Peak HR (beats . min-1) was relatively high during allegro center floor exercise, averaging 178 (92% HR max) and 158 (85% HR max) for men and women, respectively. However, these were maintained for only brief durations similar to sprint or burst activities. We conclude that these physiologic data obtained during ballet class represent only a relatively modest stimulus for augmenting aerobic (VO2max). In conjunction with the strong isometric component in ballet exercise, along with the sprint or burst component of ballet exercise, these factors would produce in elite ballet dancers VO2max values in the range of non-endurance athletes.

To further evaluate the specificity of aerobic training, maximum physiologic measures (VO2, VE, HR, and R) and submaximal exercise heart rate were determined in control (N = 8) and experimental (N = 11) subjects prior to and following 10-week interval run training. Experimental subjects significantly increased (P less than 0.01) treadmill VO2 max by 252 ml O2 or 6.3%. This was siginificantly larger (P less than 0.01) than the 87 ml O2 or 2.6% increase (P less than 0.05) observed during swimming. Max HR decreased significantly in both forms of exercise. In addition, heart rate at two submaximal work levels during running and swimming was significantly lower after training. No changes in metabolic and physiologic measures were demonstrated for the controls after the 10-wk period. These results further support the concept of the specificity of the metabolic adaptation to aerobic training and strongly suggest that local adaptations in skeletal muscle significantly contribute to improvement in VO2 max. However, running may produce a general training adaptation in maximal and submaximal heart rate.