Mark A. Schafer

Exercise Intensity and Lymphocyte Subset Apoptosis

This investigation assessed the lymphocyte subset response to increasing intensity. Participants completed an exertion test (VO(2max)), and later performed a 10-min run at 76% VO(2max), 5-min at 87%, and run to exhaustion at 100% intensity. Blood was sampled at rest, following each intensity, and 1-h post. Cell concentration, apoptosis (annexin V) and migration (CX₃CR1) were evaluated in CD4+, CD8+, and CD19+ subsets. Relative data were analyzed using 1-way ANOVA with significance at P≤0.05. Absolute changes from rest (Δ baseline) were calculated for exercise conditions. CX₃CR1 displayed relative changes 1-h post, (CD8+ Pre=58%, Post=68%, 1 h-Post=37%, P=0.04) (CD19+ Pre=1.9%, Post=3.2%, 1 h-Post=5.2%, P=0.02). No relative changes were noted for subsets and annexin V. Absolute changes revealed that CD4+/annexin V+ and CD8+/annexin V+ significantly increased at 76%,(P<0.01). Significant absolute increases were observed in CD4+/CX₃CR1 at 87% VO2max, and at 87% and 100% VO2max in CD8+/CX₃CR1 (P<0.01). Subsets respond differently with intensity with respect to cell count, and markers of apoptosis and cell migration. CD4+ and CD8+ appear to be prone to apoptosis with moderate exercise, but significant increases in migration at higher intensities suggests movement of these cells from the vasculature in postexercise measurements.

Concurrent muscle hurt and perceived exertion of children during resistance exercise.

PURPOSE Rating of muscle hurt (RMH) and RPE were concurrently measured for 10- to 14-yr-old females (n = 50) and males (n = 50) performing unilateral biceps curl (BC) and knee extension (KE) isotonic exercise. METHODS BC and KE exercises were counterbalanced within subjects. Three counterbalanced, 10 repetition sets (30%, 50%, and 70% one repetition maximum (1-RM)) were performed for both exercises. RMH and RPE were obtained for active muscles using the Childrens OMNI-Hurt Scale and the Childrens OMNI-Resistance Exercise Scale of Perceived Exertion, respectively. RESULTS For both females and males, RMH ranged across sets from 1.5 to 6.0 during BC and 3.2 to 6.7 during KE. RPE ranged from 3.4 to 8.3 during BC and 5.0 to 8.9 during KE. Ratings expressed as percent scores were lower (P < 0.01) for RMH than for RPE at the 30%, 50%, and 70% 1-RM during BC and KE for females and males. Regression coefficients for weight lifted as a function of RMH ranged from r = 0.67 to r = 0.87 (P < 0.01) for BC and KE. Correlations between RMH and RPE ranged from r = 0.19 to r = 0.82 across sets for both genders. CONCLUSIONS Female and male children can concurrently and differentially rate their perceived intensity of muscle hurt and exertion during upper and lower body resistance exercise using numerical category metrics (i.e., OMNI scales) having construct-specific pictorial and verbal descriptors.

Repeated high-intensity Wingate cycle bouts influence markers of lymphocyte migration but not apoptosis

Studies have shown significant changes in lymphocytes during continuous exercise, but little has been shown on the effect of repeated high intensity bouts. This study was designed to examine the effect of repeated intermittent bouts on lymphocyte subset cell count, apoptosis, and migration. A series of 6 Wingate anaerobic cycle tests were performed by participants (N = 8) with blood samples attained before, immediately following, and after a designated recovery period (excess postexercise oxygen consumption (EPOC)) to observe lymphocyte changes. Lymphocyte subsets (CD4+, CD4/CD45RA+, CD8+, CD8+/CD45RA+, CD19+) were assessed for apoptosis (annexin V+) and cellular migration (CX(3)CR1). Our results indicate that the CD8+ and CD8+/CD45RA+ subsets were significantly influenced by the repetitive Wingate cycling protocol such that cell counts increased with exercise, and then decreased at EPOC termination (p = 0.016). The observed postexercise decrease in CD8+ and CD8+/CD45RA+ cells was accompanied by a significant change in the CX(3)CR1 cell migration receptor (p = 0.019), but not apoptosis (p = 0.87). This indicates that with repetitive high-intensity cycling, the response in CD8+ cells following the bout is likely due to cell migration rather than cell death.

Finger-stick Blood Sampling Methodology for the Determination of Exercise-induced Lymphocyte Apoptosis

Exercise is a physiological stimulus capable of inducing apoptosis in immune cells. To date, various limitations have been identified with the measurement of this phenomenon, particularly relating to the amount of time required to isolate and treat a blood sample prior to the assessment of cell death. Because of this, it is difficult to determine whether reported increases in immune cell apoptosis can be contributed to the actual effect of exercise on the system, or are a reflection of the time and processing necessary to eventually obtain this measurement. In this article we demonstrate a rapid and minimally invasive procedure for the analysis of exercise-induced lymphocyte apoptosis. Unlike other techniques, whole blood is added to an antibody panel immediately upon obtaining a sample. Following the incubation period, red blood cells are lysed and samples are ready to be analyzed. The use of a finger-stick sampling procedure reduces the volume of blood required, and minimizes the discomfort to subjects.

Cognitive awareness of carbohydrate intake does not alter exercise-induced lymphocyte apoptosis

OBJECTIVE: The purpose of this investigation was to determine whether cognitive awareness of carbohydrate beverage consumption affects exercise‐induced lymphocyte apoptosis, independent of actual carbohydrate intake. INTRODUCTION: Carbohydrate supplementation during aerobic exercise generally protects against the immunosuppressive effects of exercise. It is not currently known whether carbohydrate consumption or simply the knowledge of carbohydrate consumption also has that effect. METHODS: Endurance trained male and female (N  =  10) athletes were randomly assigned to one of two groups based on either a correct or incorrect cognitive awareness of carbohydrate intake. In the incorrect group, the subjects were informed that they were receiving the carbohydrate beverage but actually received the placebo beverage. Participants completed a 60‐min ride on a cycle ergometer at 80% VO2peak under carbohydrate and placebo supplemented conditions. Venous blood samples were collected at rest and immediately after exercise and were used to determine the plasma glucose concentration, lymphocyte count, and extent of lymphocyte apoptosis. Cognitive awareness, either correct or incorrect, did not have an effect on any of the measured variables. RESULTS: Carbohydrate supplementation during exercise did not have an effect on lymphocyte count or apoptotic index. Independent of drink type, exercise resulted in significant lymphocytosis and lymphocyte apoptosis (apoptotic index at rest  =  6.3±3% and apoptotic index following exercise  =  11.6±3%, P<0.01). CONCLUSION: Neither carbohydrate nor placebo supplementation altered the typical lymphocyte apoptotic response following exercise. While carbohydrate supplementation generally has an immune‐boosting effect during exercise, it appears that this influence does not extend to the mechanisms that govern exercise‐induced lymphocyte cell death.

Effects of a Simulated Tennis Match on Lymphocyte Subset Measurements

Tennis is an activity requiring both endurance and anaerobic components, which could have immunosuppressive effects postexercise. Purpose The purpose of this investigation was to determine the effect of a simulated tennis match on apoptotic and migratory markers on lymphocyte subsets. Method Male high school (n = 5) and college (n = 3) tennis players (M age = 18.9 ± 3.3 years) completed 10 sets of a tennis protocol including serves, forehand strokes, and backhand groundstrokes with 1-min rest periods between sets. Apoptosis antigen 1 receptor (CD95) and chemokine receptor fractalkine (CX3CR1) expression was analyzed on helper T lymphocytes (CD4+), cytotoxic T lymphocytes (CD8+), and B lymphocytes (CD19+) twice, at resting baseline and immediately after all 10 sets of the tennis protocol. Results An increase was observed in each lymphocyte subtype (p < .02, effect size = .41), and comparison of absolute changes revealed increases in CD4+/CD95+, CD8+/CD95+, and CD8+/CX3CR1 lymphocytes following the tennis protocol (p < .01, effect size = .43), but not in CD19+ cells. Conclusions A simulated tennis match has adequate intensity to induce immune modulations in terms of increased cell death and cellular migration in T lymphocyte subsets. Lymphocytopenia following tennis play is influenced by both apoptotic and migratory mechanisms.

Intensity selection and regulation using the OMNI scale of perceived exertion during intermittent exercise

The purpose of this investigation was to determine if subjects can self-regulate exercise intensity during intermittent exercise by using ratings of perceived exertion. Thirty-one subjects completed an estimation trial maximal treadmill graded exercise test (GXT). Using the oxygen uptake and ratings of perceived exertion (RPE) from the GXT, target RPEs that corresponded to 50% and 70% of oxygen uptake reserve were determined. During the subsequent 20 min production trial, subjects titrated treadmill speed and grade to elicit the target RPEs that were presented in 2 counterbalanced orders (counterbalance order I (70%-50% of oxygen uptake reserve) or counterbalance order II (50%-70% of oxygen uptake reserve)). Heart rate (HR) and oxygen uptake were higher in the production trial compared with the estimation trial for counterbalance order I (p < 0.001) at an RPE that corresponded to 50% of oxygen uptake reserve. There was no difference in HR and oxygen uptake between the estimation and production trial for counterbalance order II (p < 0.05). HR was higher in the production trial compared with estimation trial for counterbalance order I (p < 0.05) at an RPE that corresponded to 70% of oxygen uptake reserve. There was no difference in HR between the estimation and production trials for counterbalance order II (p < 0.05). At an RPE that corresponded to 70% of oxygen uptake reserve, there was no difference in the oxygen uptake between the estimation and production trials (p < 0.05). A difference in HR (p < 0.05) and oxygen uptake (p < 0.05) between the 2 prescribed production trial intensities was indicated. The subjects were able to utilize RPE to self-regulate intensity during 20 min of exercise at varying intensity when beginning with the target RPE that corresponded to 50% of oxygen uptake reserve.

Validation of the OMNI RPE Seven Day Exertional Recall Questionnaire

Purpose: The present study examined the validity of the Seven Day Recall Questionnaire among recreationally active men and women. Method: Initially, participants completed a level walk (2.5 mph [4.0 kph]), hill walk (3.5 mph [5.6 kph], 5% grade), and run (5.0 mph [8.0 kph], 2.5% grade). Seven days later, participants were given the Seven Day Recall Questionnaire and rated their perceived exertion associated with the exercise bouts. Participants then repeated the same exercise bouts as in Session 1, and the OMNI rating of perceived exertion (RPE) was estimated. Results: Concurrent validity indicated that for both men and women, respectively, the RPE-Overall (r = .48, r = .70), RPE-Leg (r = .43, r = .66), and RPE-Chest (r = .47, r = .66) derived from the Seven Day Recall Questionnaire distributed as a function of oxygen consumption. RPE-Overall (r = .61, r = .76), RPE-Leg (r = .56, r = .72), and RPE-Chest (r = .61, r = .72) from the Seven Day Recall Questionnaire distributed as a function of heart rate. Convergent validity coefficients between the perceptual responses from the Seven Day Recall Questionnaire and the recall/criterion session were: level walk (r = .53–.87, r = .51–.80), hill walk (r = .65–.79, r = .56–.64), and run (r = .60–.68, r = .68–.78) for men and women, respectively. Conclusions: Concurrent and convergent evidence partially supports the utilization of the Seven Day Recall Questionnaire to recall the relative intensity of walking and running exercise sessions conducted 7 days prior.

Cross-validation of Peak Oxygen Consumption Prediction Models From OMNI Perceived Exertion.

This study cross-validated statistical models for prediction of peak oxygen consumption using ratings of perceived exertion from the Adult OMNI Cycle Scale of Perceived Exertion. 74 participants (men: n=36; women: n=38) completed a graded cycle exercise test. Ratings of perceived exertion for the overall body, legs, and chest/breathing were recorded each test stage and entered into previously developed 3-stage peak oxygen consumption prediction models. There were no significant differences (p>0.05) between measured and predicted peak oxygen consumption from ratings of perceived exertion for the overall body, legs, and chest/breathing within men (mean±standard deviation: 3.16±0.52 vs. 2.92±0.33 vs. 2.90±0.29 vs. 2.90±0.26 L·min(-1)) and women (2.17±0.29 vs. 2.02±0.22 vs. 2.03±0.19 vs. 2.01±0.19 L·min(-1)) participants. Previously developed statistical models for prediction of peak oxygen consumption based on subpeak OMNI ratings of perceived exertion responses were similar to measured peak oxygen consumption in a separate group of participants. These findings provide practical implications for the use of the original statistical models in standard health-fitness settings.

Caffeine affects CD8+ lymphocyte apoptosis and migration differently in naïve and familiar individuals following moderate intensity exercise

The purpose of this investigation was to determine the lymphocyte subset response to 30 min of moderate treadmill exercise during caffeine supplemented (6.0 mg.kg−1) and placebo conditions in caffeine-naïve and -familiar individuals. Seventeen individuals participated (caffeine-familiar = 8, caffeine-naïve = 9) completing two exercise bouts (caffeine supplemented and placebo control) 48 h apart in a counterbalanced and double-blinded fashion. Individuals were classified as follows: caffeine-naive <50 mg.d−1 and caffeine-familiar >200 mg.d−1. Whole blood samples were obtained at rest, 30 min after caffeine or placebo ingestion, immediately following exercise, and 1 h post exercise. Blood was used to analyze apoptosis (annexin V) and cellular migration (CX3CR1) responses in lymphocyte subsets (CD4+, CD8+, CD19+). Absolute changes from rest values were calculated and differences between conditions were determined through Chi-squared analysis with significance accepted at P <0.05. With regard to CD4+ and CD19+ lymphocytes, the interaction of caffeine and exercise did not affect naïve individuals to a greater extent immediately post exercise when compared to familiar, as similar apoptotic and migratory responses were observed (P >0.05). However, CD8+ lymphocyte cell death and migration responses were observed to be significantly greater at each sampling point in caffeine-familiar individuals (P <0.05). It is possible that chronic caffeine supplementation may prime CD8+ cell receptors for responsiveness to apoptosis and migration and the consequence of this form of immunosuppression in the post-exercise period should be determined.