A Hydrothermally Processed Maize Starch and Its Effects on Blood Glucose Levels During High-Intensity Interval Exercise.

Hetrick, MM, Naquin, MR, Gillan, WW, Williams, BM, and Kraemer, RR. A hydrothermally processed maize starch and its effects on blood glucose levels during high-intensity interval exercise. J Strength Cond Res 32(1): 3-12, 2018-A hydrothermally processed maize starch (HPMS) has been shown to blunt initial blood glucose and insulin response during endurance activity at 70% maximal oxygen uptake (V[Combining Dot Above]O2max). High-intensity interval training (HIIT) is a form of exercise that has many health benefits although it is only performed for short periods of time with interspersed rest periods. The purpose of this study was to compare the blood glucose and associated metabolic stress responses to a sprint interval cycling (SIC) exercise protocol (a form of HIIT) with and without an HPMS in a healthy population. Fourteen subjects completed a total of 4 sessions: a preliminary session, an SIC session with HPMS, an SIC session without HPMS, and a control session in which only HPMS was ingested. Blood glucose, blood lactate, respiratory exchange ratio, oxygen consumption, and rating of perceived exertion responses were recorded during the sessions. There was a significant and progressive rise in blood glucose levels during each of the cycle sprints of both exercise sessions, but not a significant difference between treatment or nontreatment SIC sessions. This is the first study to determine blood glucose responses to SIC after each sprint interval and to report that ingestion of HPMS does not affect glucose responses to SIC. The findings provide some preliminary evidence suggesting subjects at risk for glucose excursions could use SIC to improve health through monitoring blood glucose concentrations during SIC and if necessary, modifying number, intensity, and duration of sprints completed.

Validity of Wearable Activity Monitors during Cycling and Resistance Exercise.

INTRODUCTION: The use of wearable activity monitors has seen rapid growth; however, the mode and intensity of exercise could affect the validity of heart rate (HR) and caloric (energy) expenditure (EE) readings. There is a lack of data regarding the validity of wearable activity monitors during graded cycling regimen and a standard resistance exercise. The present study determined the validity of eight monitors for HR compared with an ECG and seven monitors for EE compared with a metabolic analyzer during graded cycling and resistance exercise. METHODS: Fifty subjects (28 women, 22 men) completed separate trials of graded cycling and three sets of four resistance exercises at a 10-repetition-maximum load. Monitors included the following: Apple Watch Series 2, Fitbit Blaze, Fitbit Charge 2, Polar H7, Polar A360, Garmin Vivosmart HR, TomTom Touch, and Bose SoundSport Pulse (BSP) headphones. HR was recorded after each cycling intensity and after each resistance exercise set. EE was recorded after both protocols. Validity was established as having a mean absolute percent error (MAPE) value of ≤10%. RESULTS: The Polar H7 and BSP were valid during both exercise modes (cycling: MAPE = 6.87%, R = 0.79; resistance exercise: MAPE = 6.31%, R = 0.83). During cycling, the Apple Watch Series 2 revealed the greatest HR validity (MAPE = 4.14%, R = 0.80). The BSP revealed the greatest HR accuracy during resistance exercise (MAPE = 6.24%, R = 0.86). Across all devices, as exercise intensity increased, there was greater underestimation of HR. No device was valid for EE during cycling or resistance exercise. CONCLUSIONS: HR from wearable devices differed at different exercise intensities; EE estimates from wearable devices were inaccurate. Wearable devices are not medical devices, and users should be cautious when using these devices for monitoring physiological responses to exercise.

Comparison of Cardiorespiratory and Metabolic Responses in Kettlebell High-Intensity Interval Training Versus Sprint Interval Cycling.

The purpose of this study was to determine the effectiveness of a novel exercise protocol we developed for kettlebell high-intensity interval training (KB-HIIT) by comparing the cardiorespiratory and metabolic responses to a standard sprint interval cycling (SIC) exercise protocol. Eight men volunteered for the study and completed 2 preliminary sessions, followed by two 12-minute sessions of KB-HIIT and SIC in a counterbalanced fashion. In the KB-HITT session, 3 circuits of 4 exercises were performed using a Tabata regimen. In the SIC session, three 30-second sprints were performed, with 4 minutes of recovery in between the first 2 sprints and 2.5 minutes of recovery after the last sprint. A within-subjects' design over multiple time points was used to compare oxygen consumption (V[Combining Dot Above]O2), respiratory exchange ratio (RER), tidal volume (TV), breathing frequency (f), minute ventilation (VE), caloric expenditure rate (kcal·min), and heart rate (HR) between the exercise protocols. Additionally, total caloric expenditure was compared. A significant group effect, time effect, and group × time interaction were found for V[Combining Dot Above]O2, RER, and TV, with V[Combining Dot Above]O2 being higher and TV and RER being lower in the KB-HIIT compared with the SIC. Only a significant time effect and group × time interaction were found for f, VE, kcal·min, and HR. Additionally, total caloric expenditure was found to be significantly higher during the KB-HIIT. The results of this study suggest that KB-HIIT may be more attractive and sustainable than SIC and can be effective in stimulating cardiorespiratory and metabolic responses that could improve health and aerobic performance.

An evaluation of a college exercise leader program: using exercise science students as advocates for behavior modification.

BACKGROUND: The purpose of this study was to evaluate a college's exercise leadership program, which was developed to help students, faculty and staff implement behavior changes necessary to begin and maintain a comprehensive exercise program. METHODS: From 2006-2011, a total 66 subjects were recruited and each was assigned to a student exercise leader. Based on comprehensive baseline assessments, each student designed an individualized exercise program for his/her subject. At program completion, the subjects were reassessed. RESULTS: Paired t tests were used to find significant statistical changes (P < .05) among the fitness components. Significant changes as a function of the 6-week exercise program were observed in body weight, body fat percentage, waist circumference, 1-mile walk time, sit-ups, push-ups, and trunk flexion. CONCLUSIONS: Getting started is the most difficult step, but beginning an exercise program has immediate benefits. Institutions of higher education are addressing issues of wellness as a means for increasing graduation, retention, and productivity rates among their campus constituents. These efforts are part of a collaborative effort initiated by the American College Health Association known as Healthy Campus 2020. The findings from this study have a direct impact on programmatic efforts.