Mark Blegen

The immunological and metabolic responses to exercise of varying intensities in normoxic and hypoxic environments.

Blegen, M, Cheatham, C, Caine-Bish, N, Woolverton, C, Marcinkiewicz, J, and Glickman, E. The immunological and metabolic responses to exercise of varying intensities in normoxic and hypoxic environments. J Strength Cond Res 22(5): 1638-1644, 2008-The purpose of this study was to determine the effects of varying intensities of exercise in normoxic and hypoxic environments on selected immune regulation and metabolic responses. Using a within-subjects design, subjects performed maximal tests on a cycle ergometer in both normoxic (PiO2 = 20.94%) and hypoxic (PiO2 = 14.65%) environments to determine &OV0312;O2max. On separate occasions, subjects then performed four randomly assigned, 1-hour exercise bouts on a cycle ergometer (two each in normoxic and hypoxic environments). The hypoxic environment was created by reducing the O2 concentration of inspired air using a commercially available hypoxic chamber. The intensities for the exercise bouts were predetermined as 40 and 60% of their normoxic &OV0312;O2max for the normoxic exercise bouts and as 40 and 60% of their hypoxic &OV0312;O2max for the hypoxic exercise bouts. Blood samples were collected preexercise, postexercise, 15 minutes postexercise, 2 hours postexercise, and 24 hours postexercise for the determination of interleukin-1 (IL-1), tumor necrosis factor-α (TNF-α), glucose, glycerol, free fatty acids, epinephrine, norepinephrine, and cortisol. There were no significant differences (p < 0.05) between condition or intensity for IL-1 or TNF-α. Significant differences (p < 0.05) between intensities were demonstrated for epinephrine, norepinephrine, and cortisol (p < 0.05). A significant difference was identified between normoxic and hypoxic environments with respect to nonesterifed fatty acids (0.45 ± 0.37 vs. 0.58 ± 0.31 mEq·L−1, respectively; p = 0.012). During prolonged exercise at 40 and 60% of their respective &OV0312;O2max values, hypoxia did not seem to dramatically alter the response of the selected immune system or metabolic markers. Exercise training that uses acute hypoxic environments does not adversely affect immune regulation system status and may be beneficial for those individuals looking to increase endurance performance.

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.

Motivational differences for participation among championship and non-championship caliber NCAA division III football teams.

Abstract Blegen, MD, Stenson, MR, Micek, DM, and Matthews, TD. Motivational differences for participation among championship and non-championship caliber NCAA division III football teams. J Strength Cond Res 26(11): 2924–2928. 2012—Reasons for participation in National Collegiate Athletic Association (NCAA) Division III athletics vary greatly. The purpose of this study was to investigate if differences in motivational climate existed between championship and non–championship-level NCAA Division III football teams, and differences in player status (starter vs. nonstarter). Players (N = 224) from 3 NCAA Division III football programs (1 championship level and 2 non-championship level) were recruited as participants. All players completed the Sport Motivation Scale, and the results were analyzed using a 2 × 2 multivariate analysis of variance (MANOVA) to examine differences among the motivation variables for starter vs. nonstarter and championship vs. non-championship teams. A 1-way MANOVA was used to examine differences across year in school. Dependent variables included internal motivation to experience stimulation, internal motivation for accomplishment, internal motivation for knowledge, external motivation for identification regulation, external motivation for introjection regulation, external motivation for external regulation, and amotivation. The interaction between starter status and team was not significant (&Lgr; = 0.996, p > 0.40). Additionally, there were no significant differences in the mean vector scores for starter vs. nonstarter (&Lgr; = 0.965, p = 0.378). For team type, however, differences did exist across dependent variables (&Lgr; = 0.898, p = 0.002). For all variables except amotivation, the championship-level team had significantly higher scores than the non–championship-level teams. Members of NCAA Division III championship-level football teams have higher motivation to participate in their sport compared with members of non-championship teams. These results could have an impact on player morale, coaching strategies, and future success in athletic-related activities.

A Comparison of Scholastic and Collegiate Longsnapping Techniques

The purpose of this study was to identify the differences that exist between collegiate (CS) and scholastic (SS) longsnappers. Six CS (21.4 ± 1.37 years) and 7 SS (16.7 ± 1.11 years) longsnappers were filmed performing 10 longsnaps each. The CS and SS longsnappers had 7.0 ± 0.89 and 2.7 ± 0.95 years experience longsnapping, respectively. Each of the 10 longsnaps for all subjects were analyzed for take-off velocity and accuracy. The snap that most closely approximated the individual snappers median values for takeoff velocity and accuracy was digitized using a 20-point model. CS were both faster (0.85 ± 0.10 seconds vs. 1.25 ± 0.19 seconds) and more accurate in terms of mean radial error (29.36 ± 8.4 cm vs. 47.2 ± 8.26 cm) than their SS counterparts. These differences were related to body positioning both before and during the longsnap. CS exhibited more shoulder flexion (135 ± 6.338; vs. 98 ± 9.018) and greater elbow extension (133 ± 8.18 vs. 95 ± 6.778) in the set position phase, along with greater center of mass movement (0.27 ± 0.02 m vs. 0.14 ± 0.04 m) in the anterior-posterior direction and less hip flexion (72 ± 1.858 vs. 49 ± 9.428) during the preflight phase. Longsnapping experience and accuracy were significantly related (r 520.82, p < 0.05). These results suggest that body positioning both before and during the longsnap motion significantly influence the velocity and accuracy of the longsnap.

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.

The Effects of Nicotine on the Metabolic and Hormonal Responses During Acute Cold Exposure

Abstract Objective.—To examine the effects of nicotine on the metabolic and hormonal responses during acute cold exposure. Methods.—Participants in this study included 6 men and 5 women between the ages of 19 and 25 years. Each subject performed 2 cold-air trials (CATs) consisting of a 30-minute baseline (BASE) period and a 120-minute exposure to 10°C air. One CAT was performed after a nicotine (NIC) dosing using a 21-mg transdermal patch, whereas the other CAT was performed after a placebo (PL) treatment. Blood samples for metabolic and hormonal measurements were obtained at the end of BASE and immediately after the cold exposure. Results.—When examining the sexes separately, there was no difference in norepinephrine between PL and NIC (P = .066). There was also no difference in epinephrine between PL and NIC in either sex (P = .634). From BASE to 120 minutes of the CAT, there was a significant decrease in cortisol (P = .036), but this response was similar between the 2 treatments (P = .077). Glucose and glycerol concentrations were not different between the PL and NIC treatments. At BASE, nonesterified fatty acid (NEFA) concentration was lower during PL compared with NIC (P = .021); however, at 120 minutes of the CAT, NEFA was greater during PL compared with NIC (P = .035). Conclusions.—During 120 minutes of cold exposure, NIC resulted in alterations in the responses in NEFA, whereas the other blood measurements were not significantly different between the 2 groups.

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.

THE INFLUENCE OF GENDER AND MENSTRUAL PHASE ON THERMOSENSITIVITY DURING COLD WATER IMMERSION

BACKGROUND This investigation evaluated the influence of gender and phase of menstrual cycle [follicular (FOL: days 2-6) and luteal (LUT: days 19-24) phases] on thermosensitivity and metabolic heat production (HP) during cold water immersion (20 degrees C) in 10 females (22.4 +/- 2.8 yr) and 16 males (22.4 +/- 2.9 yr). METHODS Following a 20-min baseline period (BASE), subjects were immersed until esophageal temperature (Tes) reached 36.5 degrees C or for a maximum pre-occlusion (Pre-OCC) time of 40 min. An arm and thigh cuff were then inflated to 180 and 220 mmHg, respectively, for 10 min (OCC). Following release of the inflated cuffs (Post-OCC), the slope (beta) of the relationship between the decrease in Tes and the increase in HP was used to quantify thermosensitivity. RESULTS ANOVA revealed no significant difference in thermosensitivity between phases of the menstrual cycle or between men and women (FOL = -2.76, LUT = -3.05, Males = -3.24 W x kg(-1) x degrees C(-1)). A significant (p < 0.05) main effect for gender for HP, and a significant (p < 0.05) main effect for menstrual phase for mean skin temperature (Tsk) were observed. CONCLUSIONS These data suggest, despite gender differences in HP, that the thermosensitivity of HP during cold water immersion is similar between males and females and is not influenced by menstrual cycle phase. Therefore, these data indicate that when faced with a cold challenge, women respond similarly to men in both phases of their menstrual cycle.