Hemodynamic and metabolic responses to self-paced and ramp-graded exercise testing protocols.

Recent examinations have shown lower maximal oxygen consumption during traditional ramp (RAMP) compared with self-paced (SPV) graded exercise testing (GXT) attributed to differences in cardiac output. The current study examined the differences in hemodynamic and metabolic responses between RAMP and SPV during treadmill exercise. Sixteen recreationally trained men (aged23.7 ± 3.0 years) completed 2 separate treadmill GXT protocols. SPV consisted of five 2-min stages (10 min total) of increasing speed clamped by the Borg RPE6-20 scale. RAMP increased speed by 0.16 km/h every 15 s until volitional exhaustion. All testing was performed at 3% incline. Oxygen consumption was measured via indirect calorimetry; hemodynamic function was measured via thoracic impedance and blood lactate (BLa-) was measured via portable lactate analyzer. Differences between SPV and RAMP protocols were analyzed as group means by using paired-samples t tests (R Core Team 2017). Maximal values for SPV and RAMP were similar (p > 0.05) for oxygen uptake (47.1 ± 3.4 vs. 47.4 ± 3.4 mL·kg-1·min-1), heart rate (198 ± 5 vs. 200 ± 6 beats·min-1), ventilation (158.8 ± 20.7 vs. 159.3 ± 19.0 L·min-1), cardiac output (26.9 ± 5.5 vs. 27.9 ± 4.2 L·min-1), stroke volume (SV) (145.9 ± 29.2 vs. 149.8 ± 25.3 mL·beat-1), arteriovenous oxygen difference (18.5 ± 3.1 vs. 19.7 ± 3.1 mL·dL-1), ventilatory threshold (VT) (78.2 ± 7.2 vs. 79.0% ± 7.6%), and peak BLa- (11.7 ± 2.3 vs. 11.5 ± 2.4 mmol·L-1), respectively. In conclusion, SPV elicits similar maximal hemodynamic responses in comparison to RAMP; however, SV kinetics exhibited unique characteristics based on protocol. These results support SPV as a feasible GXT protocol to identify useful fitness parameters (maximal oxygen uptake, oxygen uptake kinetics, and VT).

Speed- and Circuit-Based High-Intensity Interval Training on Recovery Oxygen Consumption.

Due to the current obesity epidemic in the United States, there is growing interest in efficient, effective ways to increase energy expenditure and weight loss. Research has shown that high-intensity exercise elicits a higher Excess Post-Exercise Oxygen Consumption (EPOC) throughout the day compared to steady-state exercise. Currently, there is no single research study that examines the differences in Recovery Oxygen Consumption (ROC) resulting from high-intensity interval training (HIIT) modalities. The purpose of this study is to review the impact of circuit training (CT) and speed interval training (SIT), on ROC in both regular exercising and sedentary populations. A total of 26 participants were recruited from the UW-Eau Claire campus and divided into regularly exercising and sedentary groups, according to self-reported exercise participation status. Oxygen consumption was measured during and after two HIIT sessions and was used to estimate caloric expenditure. There was no significant difference in caloric expenditure during and after exercise among individuals who regularly exercise and individuals who are sedentary. There was also no significant difference in ROC between regular exercisers and sedentary or between SIT and CT. However, there was a significantly higher caloric expenditure in SIT vs. CT regardless of exercise status. It is recommended that individuals engage in SIT vs. CT when the goal is to maximize overall caloric expenditure. With respect to ROC, individuals can choose either modalities of HIIT to achieve similar effects on increased oxygen consumption post-exercise.

Graded Exercise Testing Protocols for the Determination of VO2max: Historical Perspectives, Progress, and Future Considerations.

Graded exercise testing (GXT) is the most widely used assessment to examine the dynamic relationship between exercise and integrated physiological systems. The information from GXT can be applied across the spectrum of sport performance, occupational safety screening, research, and clinical diagnostics. The suitability of GXT to determine a valid maximal oxygen consumption (VO2max) has been under investigation for decades. Although a set of recommended criteria exists to verify attainment of VO2max, the methods that originally established these criteria have been scrutinized. Many studies do not apply identical criteria or fail to consider individual variability in physiological responses. As an alternative to using traditional criteria, recent research efforts have been directed toward using a supramaximal verification protocol performed after a GXT to confirm attainment of VO2max. Furthermore, the emergence of self-paced protocols has provided a simple, yet reliable approach to designing and administering GXT. In order to develop a standardized GXT protocol, additional research should further examine the utility of self-paced protocols used in conjunction with verification protocols to elicit and confirm attainment of VO2max.

Multiple Off-Ice Performance Variables Predict On-Ice Skating Performance in Male and Female Division III Ice Hockey Players.

The purpose of this study was to determine if off-ice performance variables could predict on-ice skating performance in Division III collegiate hockey players. Both men (n = 15) and women (n = 11) hockey players (age = 20.5 ± 1.4 years) participated in the study. The skating tests were agility cornering S-turn, 6.10 m acceleration, 44.80 m speed, modified repeat skate, and 15.20 m full speed. Off-ice variables assessed were years of playing experience, height, weight and percent body fat and off-ice performance variables included vertical jump (VJ), 40-yd dash (36.58m), 1-RM squat, pro-agility, Wingate peak power and peak power percentage drop (% drop), and 1.5 mile (2.4km) run. Results indicated that 40-yd dash (36.58m), VJ, 1.5 mile (2.4km) run, and % drop were significant predictors of skating performance for repeat skate (slowest, fastest, and average time) and 44.80 m speed time, respectively. Four predictive equations were derived from multiple regression analyses: 1) slowest repeat skate time = 2.362 + (1.68 x 40-yd dash time) + (0.005 x 1.5 mile run), 2) fastest repeat skate time = 9.762 - (0.089 x VJ) - (0.998 x 40-yd dash time), 3) average repeat skate time = 7.770 + (1.041 x 40-yd dash time) - (0.63 x VJ) + (0.003 x 1.5 mile time), and 4) 47.85 m speed test = 7.707 - (0.050 x VJ) - (0.01 x % drop). It was concluded that selected off-ice tests could be used to predict on-ice performance regarding speed and recovery ability in Division III male and female hockey players. Key pointsThe 40-yd dash (36.58m) and vertical jump tests are significant predictors of on-ice skating performance specific to speed.In addition to 40-yd dash and vertical jump, the 1.5 mile (2.4km) run for time and percent power drop from the Wingate anaerobic power test were also significant predictors of skating performance that incorporates the aspect of recovery from skating activity.Due to the specificity of selected off-ice variables as predictors of on-ice performance, coaches can elect to assess player performance off-ice and focus on other uses of valuable ice time for their individual teams.

Is a threshold-based model a superior method to the relative percent concept for establishing individual exercise intensity? a randomized controlled trial.

BACKGROUND: Exercise intensity is arguably the most critical component of the exercise prescription model. It has been suggested that a threshold based model for establishing exercise intensity might better identify the lowest effective training stimulus for all individuals with varying fitness levels; however, experimental evidence is lacking. The purpose of this study was to compare the effectiveness of two exercise training programs for improving cardiorespiratory fitness: threshold based model vs. relative percent concept (i.e., % heart rate reserve - HRR). METHODS: Apparently healthy, but sedentary men and women (n = 42) were randomized to a non-exercise control group or one of two exercise training groups. Exercise training was performed 30 min/day on 5 days/week for 12weeks according to one of two exercise intensity regimens: 1) a relative percent method was used in which intensity was prescribed according to percentages of heart rate reserve (HRR group), or 2) a threshold based method (ACE-3ZM) was used in which intensity was prescribed according to the first ventilatory threshold (VT1) and second ventilatory threshold (VT2). RESULTS: Thirty-six men and women completed the study. After 12weeks, VO2max increased significantly (p < 0.05 vs. controls) in both HRR (1.76 ± 1.93 mL/kg/min) and ACE-3ZM (3.93 ± 0.96 mL/kg/min) groups. Repeated measures ANOVA identified a significant interaction between exercise intensity method and change in VO2max values (F = 9.06, p < 0.05) indicating that VO2max responded differently to the method of exercise intensity prescription. In the HRR group 41.7 % (5/12) of individuals experienced a favorable change in relative VO2max (Δ > 5.9 %) and were categorized as responders. Alternatively, exercise training in the ACE-3ZM group elicited a positive improvement in relative VO2max (Δ > 5.9 %) in 100 % (12/12) of the individuals. CONCLUSIONS: A threshold based exercise intensity prescription: 1). elicited significantly (p < 0.05) greater improvements in VO2max, and 2). attenuated the individual variation in VO2max training responses when compared to relative percent exercise training. These novel findings are encouraging and provide important preliminary data for the design of individualized exercise prescriptions that will enhance training efficacy and limit training unresponsiveness. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: ID NCT02351713 Registered 30 January 2015.

A community-based exercise intervention transitions metabolically abnormal obese adults to a metabolically healthy obese phenotype.

BACKGROUND: Lower habitual physical activity and poor cardiorespiratory fitness are common features of the metabolically abnormal obese (MAO) phenotype that contribute to increased cardiovascular disease risk. The aims of the present study were to determine 1) whether community-based exercise training transitions MAO adults to metabolically healthy, and 2) whether the odds of transition to metabolically healthy were larger for obese individuals who performed higher volumes of exercise and/or experienced greater increases in fitness. METHODS AND RESULTS: Metabolic syndrome components were measured in 332 adults (190 women, 142 men) before and after a supervised 14-week community-based exercise program designed to reduce cardiometabolic risk factors. Obese (body mass index ≥30 kg · m(2)) adults with two to four metabolic syndrome components were classified as MAO, whereas those with no or one component were classified as metabolically healthy but obese (MHO). After community exercise, 27/68 (40%) MAO individuals (P<0.05) transitioned to metabolically healthy, increasing the total number of MHO persons by 73% (from 37 to 64). Compared with the lowest quartiles of relative energy expenditure and change in fitness, participants in the highest quartiles were 11.6 (95% confidence interval: 2.1-65.4; P<0.05) and 7.5 (95% confidence interval: 1.5-37.5; P<0.05) times more likely to transition from MAO to MHO, respectively. CONCLUSION: Community-based exercise transitions MAO adults to metabolically healthy. MAO adults who engaged in higher volumes of exercise and experienced the greatest increase in fitness were significantly more likely to become metabolically healthy. Community exercise may be an effective model for primary prevention of cardiovascular disease.

The effects of BungeeSkate training on measures of on-ice acceleration and speed.

PURPOSE: Previous research has stated that dryland sled pulling trains first-step quickness in hockey players. Further research has demonstrated that off-ice horizontal training (sled pull, parachute, etc) relates well to on-ice acceleration and speed. However, there is limited literature pertaining to on-ice resistance training that aims to enhance speed and acceleration in hockey players. The purpose of the current study was to determine if on-ice BungeeSkate training would improve on-ice speed and acceleration in youth hockey players. METHODS: Twenty-three Peewee and Bantam hockey players (age 11-14) were recruited, with 20 participants completing the study. Pretesting and posttesting consisted of an on-ice 44.8-m speed test, a 6.1-m acceleration test, and a 15.2-m full-speed test. The training protocol consisted of 8 sessions of 5 BungeeSkate training exercises per session, 2 times per week for a 4-wk period. RESULTS: The results of this study showed that speed and top speed were significantly increased (P < .05) by 4.2% and 4.3%, respectively. Acceleration was also slightly improved but not significantly. CONCLUSIONS: A 4-wk BungeeSkate training intervention can improve acceleration and speed in youth hockey players. This training method could be a valid adjunct to existing strategies to improve skill development in hockey and is shown to improve speed and acceleration in relatively short training sessions. This may be most advantageous for hockey coaches and players who are looking to maximize training benefits with limited ice time.

A comparison of VO2max and metabolic variables between treadmill running and treadmill skating.

The purpose of this study was to determine differences in VO2max and metabolic variables between treadmill running and treadmill skating. This study also examined VO2max responses during a continuous skating treadmill protocol and a discontinuous skating treadmill protocol. Sixteen male high school hockey players, who had a mean age of 16 +/- 1 years and were of an above-average fitness level, participated in this study. All subjects completed 4 exercise trials: a 1-hour skating treadmill familiarization trial, a treadmill running trial, and 2 randomized skating treadmill trials. Minute ventilation (VE), oxygen consumption VO2), carbon dioxide production VCO2), respiratory exchange ratio (RER), and heart rate were averaged every 15 seconds up to VO2max for each exercise test. The results showed that there was a significant difference (P < 0.05) for VO2max (mL.kg.min) and maximal VCO2 (L.min) between the running treadmill protocol and discontinuous skating treadmill protocol. There was also a significant difference for maximal RER between the discontinuous and continuous skating treadmill protocol and between the discontinuous skating treadmill protocol and running treadmill protocol. In conclusion, the running treadmill elicited a greater VO2max (mL.kg.min) than the skating treadmill did, but when it comes to specificity of ice skating, the skating treadmill may be ideal. Also, there was no significant difference between the discontinuous and continuous skating treadmill protocols. Therefore, a continuous protocol is possible on the skating treadmill without compromising correct skating position and physiologic responses. However, the continuous skating treadmill protocol should undergo validation before other scientists, coaches, and strength and conditioning professionals can apply it correctly.

Comparison of DXA, Siri's 2C, and Lohman' s Db-mineral models for estimating the body fat of physically active adults.

The authors used 3-component (3C) Db-mineral-model (Lohman, 1986) reference measures to cross-validate Siri's (1961) 2-component (2C) conversion formula and dual-energy X-ray absorptiometry (DXA) estimates of relative body fat (%BF) for physically active adults. Participants varied in age (18 to 59 y), body fatness, ethnicity (black, Hispanic, white), and physical activity level. The 3C Db-mineral model was used to obtain reference measures of % BF (%BF3C) for comparison with body-composition measures from DXA and hydrodensitometry. For men (n = 110) and women (n= 110), %BF3C (14.0 % BF and 24.4 % BF, respectively) was more accurately estimated by Siri's 2C formula (% FSiri; men, r = 0.97, SEE = 1.77 % BF; women, r = 0.98, SEE = 1.56 % BF) than by DXA (% FDXA; men, r = 0.86, SEE = 3.54 % BF; women, r =0.88, SEE = 3.73 % BF). The average %BFSiri (men, 15.8 % BF; women, 24.7 % BF) and % FDXA (men, 16.2 % BF; women, 26.0 %BF) differed significantly (P < 0.001) from %BF3C. Siri's 2C model estimated the average % BF3C in this sample more accurately than DXA did.