Whey protein improves glycemia during an oral glucose tolerance test compared to vigorous-intensity aerobic exercise in young adult men.

BACKGROUND: Both aerobic exercise and whey protein can improve glucose regulation. The purpose of this study was to investigate how a single bout of vigorous-intensity aerobic exercise and whey protein, independently, as well as when combined, influence glycemia during an oral glucose tolerance test in sedentary, young men. METHODS: Healthy males (n = 11) completed four randomized trials: no exercise/no whey protein (R); exercise (EX; walking at 70% VO2max for 60 min); 50 g of whey protein (W); and exercise combined with 50 g of whey protein (EXW). Each trial included a 75 g oral glucose tolerance test (OGTT) that was completed after an overnight fast. Blood samples were collected over a two-hour period during the OGTT. For EX and EXW, the exercise was performed the evening before the OGTT and the 50 g of whey protein was dissolved in 250 mL of water and was consumed as a preload 30 min prior to the OGTT. For R and EX, participants consumed 250 mL of water prior to the OGTT. Plasma samples were analyzed for glucose, insulin, C-peptide, glucagon, gastric inhibitory peptide (GIP) and glucagon like peptide 1 (GLP-1), and postprandial incremental area under the curve (iAUC) was calculated for each. RESULTS: Glucose iAUC was reduced during W (- 32.9 ± 22.3 mmol/L) compared to R (122.7 ± 29.8 mmol/L; p < 0.01) and EX (154.3 ± 29.2 mmol/L; p < 0.01). Similarly, glucose iAUC was reduced for EXW (17.4 ± 28.9 mmol/L) compared to R and EX (p < 0.01 for both). There were no differences in iAUC for insulin, C-peptide, GIP, GLP-1, and glucagon between the four trials. Insulin, C-peptide, glucagon, GIP, and GLP-1 were elevated during the whey protein preload period for W and EXW compared to EX and R (p < 0.01). There were no differences for insulin, C-peptide, glucagon, GIP, or GLP-1 between trials for the remaining duration of the OGTT. CONCLUSIONS: Glucose responses during an oral glucose tolerance test were improved for W compared to EX. There were no additional improvements in glucose responses when vigorous-intensity aerobic exercise was combined with whey protein (EXW).

Cardiorespiratory responses to acute bouts of high-intensity functional training and traditional exercise in physically active adults.

BACKGROUND: High-intensity functional training is a popular form of exercise, but little is known about how it compares to more traditional exercise patterns. METHODS: Thirty healthy, physically active adults (15 males, 15 females) performed a high-intensity functional training workout (HIFT) and a traditional workout (TRAD). Cardiorespiratory responses were measured during and for 15 min after each workout. RESULTS: Peak heart rate (males: 187±7 vs. 171±10 bpm, P<0.001; females: 191±9 vs. 175±6 bpm, P<0.001), peak VO2 (males: 3.80±0.58 vs. 3.26±0.60 L/min, P<0.001; females: 2.65±0.26 vs. 2.36±0.21, P<0.001), and average 15 min recovery VO2 (males: 1.15±0.20 vs. 0.99±0.17 L/min, P<0.001; females: 0.77±0.10 vs. 0.71±0.07 L/min, P=0.019) were significantly higher in HIFT vs. TRAD. Aerobic energy expenditure was significantly higher in HIFT compared to TRAD in males (9.01±1.43 vs. 8.53±1.38 kcal/min, P=0.002) but was not significantly different between the two workouts in females (6.04±0.53 vs. 5.97±0.50 kcal/min, P=0.395). Postexercise systolic blood pressure (SBP) was significantly higher than pre-exercise SBP following both HIFT (males: 124±13 mmHg pre to 154±28 mmHg post, P<0.001; females: 110±7 mmHg pre to 140±15 mmHg post, P<0.001) and TRAD (males: 124±13 mmHg pre to 142±16 mmHg post, P=0.002; females: 112±8 mmHg pre to 123±10 mmHg post, P=0.002), however, HIFT led to a greater increase compared to TRAD in females (P=0.001). Postexercise diastolic blood pressure (DBP) was significantly lower than pre-exercise DBP following both HIFT (males: 77±9 mmHg pre to 64±6 mmHg post, P<0.001; females: 71±8 mmHg pre to 64±7 mmHg post, P=0.011) and TRAD (males: 82±7 mmHg pre to 72±7 mmHg post, P<0.001; females: 73±8 mmHg pre to 65±8 mmHg post, P<0.001). Mean arterial blood pressure was unchanged following both workouts. CONCLUSIONS: High-intensity functional training may be an effective form of exercise for caloric expenditure and may elicit greater cardiorespiratory stress than traditional exercise.

Consecutive days of exercise decrease insulin response more than a single exercise session in healthy, inactive men.

PURPOSE: It is reported that a single bout of exercise can lower insulin responses 12-24 h post-exercise; however, the insulin responses to alternate or consecutive bouts of exercise is unknown. Thus, the purpose of this study was to examine the effect of exercise pattern on post-exercise insulin and glucose responses following a glucose challenge. METHODS: Ten male participants (n = 10, mean ± SD, Age 29.5 ± 7.7 years; BMI 25.7 ± 3.0 kg/m2) completed three exercise trials of walking for 60 min at ~ 70% of VO2max. The trials consisted of: three consecutive exercise days (3CON), three alternate exercise days (3ALT), a single bout of exercise (SB), and a no exercise control (R). Twelve to fourteen hours after the last bout of exercise or R, participants completed a 75 g oral glucose tolerance test (OGTT) and blood was collected at 30 min intervals for the measurement of glucose, insulin, and C-peptide. RESULT: Calculated incremental area under the curve (iAUC) for glucose and C-peptide was not different between the four trials. Insulin iAUC decreased 34.9% for 3CON compared to R (p < 0.01). CONCLUSION: Three consecutive days of walking at ~ 70% VO2max improved insulin response following an OGTT compared to no exercise. It is possible, that for healthy males, the effect of a single bout of exercise or exercise bouts separated by more than 24 h may not be enough stimulus to lower insulin responses to a glucose challenge.

Physiological and Fitness Adaptations after Eight Weeks of High-Intensity Functional Training in Physically Inactive Adults.

The purpose of this study was to characterize high-intensity functional training (HIFT) in physically inactive adults. Four men and 10 women who were inexperienced with HIFT and not performing regular physical activity performed HIFT 3 days/week for 8 weeks. Health and fitness measures were assessed before and after the intervention. Resting heart rate (73 ± 12 vs. 68 ± 11 bpm) and resting diastolic blood pressure (71 ± 7 vs. 65 ± 6 mmHg) were reduced, while resting systolic blood pressure remained unchanged. Absolute VO2max (2.53 ± 0.68 vs. 2.69 ± 0.66 L/min) and relative VO2max (32.51 ± 8.84 vs. 34.31 ± 8.63 mL/kg/min) were improved. Lean body mass (48.20 ± 13.37 vs. 49.26 ± 13.81 kg) was increased, but fat mass was unchanged. Performance on the leg press (164.61 ± 54.35 vs. 201.62 ± 67.50 kg), bench press (39.12 ± 20.15 vs. 46.43 ± 21.18 kg), YMCA bench press (26 ± 13 vs. 37 ± 16 reps), one-minute sit-up (25 ± 9 vs. 32 ± 10 reps), and sit-and-reach (30.36 ± 11.36 vs. 32.14 ± 9.66 cm) were all increased. High-intensity functional training may be useful for improving health-related physical fitness parameters in physically inactive adults.