Cardiovascular adjustments to exercise distributed between the upper and lower body.

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.

Cross-modal exercise prescription at absolute and relative oxygen uptake using perceived exertion.

Cross-modal exercise prescription at absolute and relative oxygen uptake using perceived exertion. Med. Sci. Sports Exerc., Vol. 22, No. 5, pp. 653-659, 1990. The validity of cross-modal prescription of exercise intensity based on rated perceived exertion (RPE) was determined for eight men (26 +/- SE 1.9 yr) at absolute and relative VO2. Exercise modes were treadmill (TM), cycle ergometer (C), and bench stepping while pumping 0.91 kg handweights (HB). Relative (Rel) constant load sessions were performed for each mode at 70% of mode-specific VO2 peak. Absolute (Absol) constant load sessions were performed for C and HB at the VO2 equivalent to 70% of TM VO2 peak. The five 12 min sessions were presented on separate days in random order. RPE-Overall during TM-Rel (11.1) was a) lower (P less than 0.05) than C-Absol (12.6) and HB-Absol (12.5) and b) the same as C-Rel (11.3) and HB-Rel (10.7). RPE-Legs during TM-Rel was a) lower (P less than 0.05) than C-Absol and HB-Absol and b) the same as C-Rel and HB-Rel. RPE-Chest a) did not differ between TM-Rel and C-Absol or HB-Absol and b) was lower (P less than 0.05) for C-Rel and HB-Rel than TM-Rel. RPE-Arms was higher (P less than 0.05) for C-Absol, HB-Absol, and HB-Rel than TM-Rel but did not differ between TM-Rel and C-Rel. Oxygen uptake, heart rate, and ventilation during TM-Rel were a) the same as C-Absol and HB-Absol and b) higher (P less than 0.05) than C-Rel and HB-Rel. Perceptually based cross-modal prescription of exercise intensity using a psychophysical estimation method is valid provided that the physiological reference is the relative, not the absolute, VO2.

The influence of ethnicity on thermosensitivity during cold water immersion.

PURPOSE: This investigation evaluated the influence of ethnicity, Caucasian (CAU) vs. African American (AA), on thermosensitivity and metabolic heat production (HP) during cold water immersion (20 degrees C) in 15 CAU (22.7 +/- 2.7 yr) vs. 7 AA (21.7 +/- 2.7 yr) males. METHODS: Following a 20-min baseline period (BASE), subjects were immersed in 20 degrees C water until esophageal temperature (Tes) reached 36.5 degrees C or for a maximum pre-occlusion (Pre-OCC) time of 40 min. Arm and thigh cuffs were then inflated to 180 and 220 mm Hg, respectively, for 10 min (OCC). Following release of the inflated cuffs (Post-OCC), the slope of the relationship between the decrease in Tes and the increase in HP was used to define thermosensitivity (beta). RESULTS: ANOVA revealed no significant difference in thermosensitivity between CAU and AA (CAU = 3.56 +/- 1.54 vs. AA = 2.43 +/- 1.58 W.kg(-1). degrees C(-1)). No significant differences (p > 0.05) were found for Tsk (CAU = 24.2 +/- 1.1 vs. AA = 25.1 +/- 1.1 degrees C) or HP (p > 0.05; CAU = 2.5 +/- 0.8 vs. AA = 36.5 +/- 1.8 W.kg(-1)). However, a significant (p < 0.05) main effect for ethnicity for Tes was observed (CAU = 36.7 +/- 1.8 vs. AA = 36.5 +/- 1.8 degrees C). CONCLUSION: These data suggest, despite a differential response in Tes between AA and CAU groups, the beta of HP during cold water immersion is similar between CAU and AA. Therefore, these data demonstrate that when faced with a cold challenge, there is a similar response in HP between CAU and AA that is accompanied by a differential response in Tes.

Serum insulin like growth factor-1 is associated with working memory, executive function and selective attention in a sample of healthy, fit older adults.

The present study examined the association between serum insulin like growth factor-1 (IGF-1) concentrations and cognitive function in a sample of healthy, fit older adults (age: 70.8±9.3 years, body mass index (BMI): 27.3±5.7). Participants reported to the laboratory and basic anthropometric data were collected, followed by a fasted blood draw to quantify serum IGF-1. Participants then underwent cognitive testing that included the Mini-Mental Status Exam (MMSE), Trail Making Test A and B, Ruff's 2 and 7 test of selective attention and Letter Number Sequencing. Results showed the participants were generally cognitively intact (MMSE 27.6±1.8). Significant partial correlations (controlled for age, gender and years of education) emerged between serum IGF-1 concentrations and the total (r=0.381, P=0.030) and longest trial (r=0.455, P=0.011) on Letter Number Sequencing. Similar partial correlations yielded significant relationships between serum IGF-1 and Ruff's Automatic Detection Errors (r=-0.495, P=0.006), Controlled Speed Errors (r=-0.598, P=0.002) and errors made on the Trial Making Test part B (r=-0.466, P=0.010). These findings suggest that fasting levels of serum IGF-1 are related to higher levels of cognitive performance in healthy older adults, including working memory, selective attention and executive function. Further work is needed to more clearly determine possible mechanisms.

Aerobic metabolic requirements of simulated cross-country skiing.

This study evaluated the aerobic metabolic requirements of simulated cross-country skiing. Five male subjects exercised on a cross-country skiing machine at 12 different arm and leg resistances and movement frequencies. Oxygen consumption (VO2) ranged from 21.6 to 44.4 ml kg(-1) min(-1). The VO2 increased significantly (p less than 0.05) as the frequency of limb movement was increased. These data suggest that simulated cross-country skiing places a significant demand on the aerobic metabolic system and as such is a viable alternative to conventional cardiovascular exercise modalities.