Biomedical subjects

C C Cheatham

Publications and source records attributed to C C Cheatham.

6 recordsLinked to original sources

PubMed2004

Running performance in middle-school runners.

AIM: This study examined the relationship of 3-km run time to indices of aerobic and anaerobic ability in 9 male runners (13.4+/-0.6 years, mean+/-SD). METHODS: Anthropometric measurements were made, and an exercise test to determine running economy at 187 m x min(-1) and (.-)VO(2max) were assessed on a treadmill. On a separate day, 2 55-m sprints followed by a 3-km run were performed on a 200-m indoor track. Capillary blood samples were obtained from a finger tip immediately after the run to determine blood lactate level. Fractional utilization (%(.-)VO(2max) used during the 3-km run) was calculated. Correlations were used to examine the relationship between run time and the physiological measurements. RESULTS: Mean values for (.-)VO(2), HR and RER at maximal exercise were 61.7+/-4.4 ml x kg(-1)xmin(-1), 198.9+/-6.7 b x min(-1), and 1.16+/-0.04, respectively. The average time to run 3 km was 13.27+/-0.97 min (90.1+/-7.2% of (.-)VO(2max)). Post-run blood lactate level was 8.3+/-3.2 mmol x L(-1) and was significantly related (r=-0.73, p=0.02) to 3-km time. Fractional utilization tended to be related (r=-0.56, p=0.12) to time. CONCLUSIONS: In this age group the ability to run at a high percentage of (.-)VO(2max) and tolerate a high blood lactate appear to be important determinants of running performance in young male runners.

Adolescent↗

PubMed2002

The influence of age on thermosensitivity during cold water immersion.

OBJECTIVE: This investigation evaluated the influence of older age (OLD) vs younger age (YNG) on thermosensitivity and metabolic heat production (HP) during cold water immersion (20 degrees C) in 15 YNG (22.7 +/- 2.7 years) vs 7 OLD (41.7 +/- 2.7 years) individuals. METHODS: After a 20-minute baseline (BASE) period, subjects were immersed in 20 degrees C water until esophageal temperature (Tes) reached 36.5 degrees C, or for a maximum preocclusion (pre-OCC) time of 40 minutes. Arm and thigh cuffs were then inflated to 180 and 220 mm Hg, respectively, for 10 minutes (termed "occlusion" [OCC]). After release of the inflated cuffs (postocclusion [post-OCC]), the slope (beta) of the relationship between the decrease in Tes and the increase in HP was used to quantify thermosensitivity. RESULTS: Analysis of variance showed no significant difference in thermosensitivity between OLD and YNG (OLD = 2.25 +/- 1.72 W x kg(-1) x degrees C(-1) vs YNG = 3.56 +/- 1.53 W x kg(-1) x degrees C(-1)). No significant differences (P > .05) were found for mean skin temperature (Tsk; OLD = 23.8 degrees C +/- 0.31 degrees C vs YNG = 24.2 degrees C +/- 0.19 degrees C), HP (P > .05; OLD = 3.10 +/- 0.38 W x kg(-1) vs YNG = 2.50 +/- 0.22 W x kg(-1)), or Tes (OLD = 36.61 degrees C +/- 0.11 degrees C vs YNG = 36.74 degrees C +/- 0.06 degrees C). CONCLUSIONS: Therefore, these data demonstrate that when faced with a cold challenge, there is a similar response in beta, HP, Tes, and Tsk between OLD and YNG individuals.

Adult↗

PubMed2001

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.

Adult↗

PubMed2000

Cardiovascular responses during prolonged exercise at ventilatory threshold in boys and men.

PURPOSE: The purpose of this study was to examine the cardiovascular responses during prolonged exercise in boys and men at an intensity set relative to ventilatory threshold (VT). METHODS: Eight boys (10-13 yr) and 10 men (18-25 yr) completed an orientation trial, a maximal exercise test, and a 40-min submaximal exercise bout at an intensity equal to the VO2 at VT (approximately 64.5% VO2max). RESULTS: Heart rate (HR) was higher and stroke volume (SV) was lower in the boys compared with the men (P < or = 0.05). From 10 to 40 min, HR significantly increased 9.5% and 13.6% and SV significantly decreased 8.8% and 11.6% in the boys and men, respectively. Despite the tendency for the changes in HR and SV to be greater in the men, the group-by-time interaction was not significant. Cardiac output was greater in the men (P < or = 0.05) but remained constant over time (P > 0.05). In men, mean arterial blood pressure was higher (P < or = 0.05) and decreased 4.2% over time. In boys, mean arterial blood pressure remained constant, which resulted in a significant group-by-time interaction. Total peripheral resistance (TPR) was significantly higher in the boys and remained constant over time (P > 0.05). From 0 to 40 min, the decrease in plasma volume was significantly greater in the men (-10.2%) than the boys (-5.7%) but was unrelated to the changes in SV in either group (P > 0.05). CONCLUSION: In conclusion, the cardiovascular responses during prolonged exercise are similar in boys and men, although there is a tendency for the magnitude of cardiovascular drift to be greater in the men.

Adolescent↗

PubMed2000

The effects of gender and menstrual phase on carbohydrate utilization during acute cold exposure.

OBJECTIVE: The purpose of this study was to evaluate the effects of gender and menstrual cycle on the percent of carbohydrate (CHO) utilized during cold water immersion (20 degrees C). Previous research has suggested that males and females utilize CHO differently during submaximal exercise. This study examined whether this differential response is replicated during a submaximal elevation in metabolism, as demonstrated during thermogenesis (i.e., shivering during acute cold exposure). METHODS: Male and female subjects between the ages of 18 and 30 years were recruited for this study. Female subjects underwent the experimental trial once during the follicular phase and once during the luteal phase of their menstrual cycle. Subjects were immersed to the first thoracic vertebra until esophageal temperature reached 36.5 degrees C or for a maximum preocclusion period of 40 minutes. Peripheral temperature homeostasis via cuff occlusion (right arm and left leg) took place for 10 minutes, after which the pressure cuffs were released (postocclusion) and the subjects remained in the water for an additional 10 minutes. The following variables were measured: respiratory exchange ratio, percent of CHO utilization, and oxygen consumption (Vo2). RESULTS: Analysis of variance demonstrated no significant difference between genders or phases of the menstrual cycle in respiratory exchange ratio, percent CHO utilization, or Vo2 during cold water immersion. A significant difference was observed between men and women for absolute Vo2. CONCLUSIONS: These data suggest that although men and women differ with respect to absolute aerobic metabolism, this distinction does not cause a differential response with respect to substrate utilization during acute cold exposure.

Adolescent↗

PubMed2000

Influence of gender and menstrual cycle on a cold air tolerance test and its relationship to thermosensitivity.

This investigation evaluated the influence of gender and phase of menstrual cycle [follicular (FOL): Days 2-6) and luteal (LUT: Days 19-24)] on a cold air tolerance test (CATT: 90-min of exposure to 5 degrees C air) in 8 females (22.7 +/- 3.0 yr) and 15 males (22.3 +/- 2.9 yr). In addition, central thermosensitivity (beta; W x kg(-1) x degrees C(-1) [i.e., the slope of the relationship between the decrease in esophageal temperature (Tes) and the increase in heat production (HP)], gathered during a separate water trial in 20 degrees C water, was correlated to the change (delta) in Tes and HP across the 90 min of resting exposure during the CATT. Analysis of variance revealed no significant differences between phase of menstrual cycle or gender for HP, mean skin temperature (Tsk), and insulation; however, a main effect for time for these parameters was demonstrated. Despite these similarities, Tes differed (P < 0.05) between males and females. Additionally, no relationship was found between beta and deltaHP and deltaTes in the males and females. Also, there was no relationship between beta and thermoregulation during the CATT in these subjects. These data suggest that menstrual cycle phase did not cause a differential response in Tes, Tsk, and HP during a CATT. Furthermore, women maintained a higher Tes than men during the CATT despite similarities in HP and Tsk.

Adolescent↗