A Preliminary Investigation into the Frequency Dose Effects of High-Intensity Functional Training on Cardiometabolic Health.

The objective of this study was to explore the effects of three weekly frequency doses of high-intensity functional training (HIFT) on an array of cardiometabolic markers in adults with metabolic syndrome (MetS). Twenty-one men and women, randomized into one (HIFT1), two (HIFT2), or three (HIFT3) days per week of HIFT, completed 3-weeks of familiarization plus a 12-week progressive training program. Pre- and post-intervention, several cardiometabolic, body composition, oxygen consumption, metabolic syndrome severity, and perceptions of fitness measurements were assessed. Additionally, an exercise enjoyment survey was administered post-intervention. A Cohen's d was used to demonstrate within-group change effect size. Although this study was not fully powered, a one-way and two-way ANOVA were used to compare the dose groups to provide provisional insights. No differences were found when frequency dose groups were compared. Many cardiometabolic, body composition, and fitness improvements were seen within each group, with clinically meaningful improvements in the metabolic syndrome severity score (MSSS) (HIFT1: -0.105, d = 0.28; HIFT2: -0.382, d = 1.20; HIFT3: -0.467, d = 1.07), waist circumference (HIFT1: -4.1cm, d = 3.33; HIFT2: -5.4cm, d = 0.89; HIFT3: -0.7cm, d = 0.20), and blood glucose (HIFT1: -9.5mg/dL, d = 0.98; HIFT2: -4.9mg/dL, d = 1.00; HIFT3: -1.7mg/dL, d = 0.23). All three groups similarly reported high exercise enjoyment and likeliness to continue after the intervention. In conclusion, HIFT performed once, twice, or thrice a week elicits improvements in MetS and is considered enjoyable. HIFT, even at a low weekly dose, therefore represents a potential strategy to reduce the global MetS burden.

Scaling-Up Adolescent High-Intensity Interval Training Programs for Population Health.

High-intensity interval training (HIIT) has become a polarizing form of exercise. In this article, we argue that adolescent HIIT programs can have population health impact if they are (i) integrated into existing opportunities, (ii) designed to develop physical literacy, (iii) delivered in an engaging manner, and (iv) guided and supported by an implementation framework that addresses relevant barriers and facilitators.

The Effects of a Single Session of High Intensity Functional Training on Energy Expenditure, VO2, and Blood Lactate.

High intensity functional training (HIFT) provides a potential option to meet public exercise recommendations for both cardiorespiratory and strength outcomes in a time efficient manner. To better understand the potential for HIFT as an exercise approach, energy expenditure (EE) and relative intensity need quantifying. In thirteen sedentary men and women with metabolic syndrome (MetS), we used both indirect calorimetry and blood lactate levels to calculate EE of a single session of HIFT. The HIFT session included four, 6-minute sets of consecutive functional exercises. Examples of the exercises involved were squats, deadlifts, suspension rows, suspension chest press, and planks. Intensity is described relative to individual ventilatory thresholds. The total group EE was 270.3 ± 77.3 kcal with approximately 5% attributed anaerobic energy production. VO2 ranged between 88.8 ± 12.3% and 99 ± 12% of the second ventilatory threshold (VT2), indicating a vigorous effort. After each work interval, peak blood lactate ranged between 7.9 ± 1.9 and 9.3 ± 2.9 mmol, and rate of perceived exertion between 6.9 ± 1.0 and 8.7 ± 0.8 arbitrary units from 1-10. These were achieved in approximately 46 minutes of exercise per participant. In conclusion, HIFT elicits the energy expenditure and effort requisite to result in the adaptive responses to produce the known suite of benefits of exercise for individuals with MetS.

Acute Responses to Resistance and High-Intensity Interval Training in Early Adolescents.

Harris, NK, Dulson, DK, Logan, GRM, Warbrick, IB, Merien, FLR, and Lubans, DR. Acute responses to resistance and high-intensity interval training in early adolescents. J Strength Cond Res 31(5): 1177-1186, 2017-The purpose of this study was to compare the acute physiological responses within and between resistance training (RT) and high-intensity interval training (HIIT) matched for time and with comparable effort, in a school setting. Seventeen early adolescents (12.9 ± 0.3 years) performed both RT (2-5 repetitions perceived short of failure at the end of each set) and HIIT (90% of age-predicted maximum heart rate), equated for total work set and recovery period durations comprising of 12 "sets" of 30-second work followed by 30-second recovery (total session time 12 minutes). Variables of interest included oxygen consumption, set and session heart rate (HR), and rate of perceived exertion, and change in salivary cortisol (SC), salivary alpha amylase, and blood lactate (BL) from presession to postsession. Analyses were conducted to determine responses within and between the 2 different protocols. For both RT and HIIT, there were very large increases pretrial to posttrial for SC and BL, and only BL increased greater in HIIT (9.1 ± 2.6 mmol·L) than RT (6.8 ± 3.3 mmol·L). Mean set HR for both RT (170 ± 9.1 b·min) and HIIT (179 ± 5.6 b·min) was at least 85% of HRmax. V[Combining Dot Above]O2 over all 12 sets was greater for HIIT (33.8 ± 5.21 ml·kg·min) than RT (24.9 ± 3.23 ml·kg·min). Brief, repetitive, intermittent forays into high but not supramaximal intensity exercise using RT or HIIT seemed to be a potent physiological stimulus in adolescents.

Adolescent physical activity levels: discrepancies with accelerometer data analysis.

This study investigated the effects of epoch length and cut point selection on adolescent physical activity intensity quantification using vertical axis and vector magnitude (VM) measurement with the ActiGraph GT3X+ accelerometer. Four hundred and nine adolescents (211 males; 198 females) aged 12-16 years of age wore accelerometers during waking hours. The GT3X+ acceleration counts were reintegrated into 1, 5, 15, 30 and 60 s epoch lengths for both vertical axis and VM counts. One cut point was applied to vertical axis counts and three different cut points were applied to VM counts for each epoch length. Significant differences (P < 0.01) in mean total counts per day were observed between vertical axis and VM counts, and between epoch lengths for VM only. Differences in physical activity levels were observed between vertical and VM cut points, and between epoch lengths across all activity intensities. Our findings illustrate the magnitude of differences in physical activity outcomes that occur between axis measurement, cut points and epoch length. The magnitude of difference across epoch length must be considered in the interpretation of accelerometer data and seen as a confounding variable when comparing physical activity levels between studies.

Acute Physiological Responses to Strongman Training Compared to Traditional Strength Training.

Strongman training (ST) has become an increasingly popular modality, but data on physiological responses are limited. This study sought to determine physiological responses to an ST session compared to a traditional strength exercise training (RST) session. Ten healthy men (23.6 ± 27.5 years, 85.8 ± 10.3 kg) volunteered in a crossover design, where all participants performed an ST session, an RST session, and a resting session within 7 days apart. The ST consisted of sled drag, farmer's walk, 1 arm dumbbell clean and press, and tire flip at loads eliciting approximately 30 seconds of near maximal effort per set. The RST consisted of squat, deadlift, bench press, and power clean, progressing to 75% of 1 repetition maximum. Sessions were equated for approximate total set duration. Blood lactate and salivary testosterone were recorded immediately before and after training sessions. Heart rate, caloric expenditure, and substrate utilization were measured throughout the resting session, both training protocols and for 80 minutes after training sessions. Analyses were conducted to determine differences in physiological responses within and between protocols. No significant changes in testosterone occurred at any time point for either session. Lactate increased significantly immediately after both sessions. Heart rate, caloric expenditure, and substrate utilization were all elevated significantly during ST and RST. Heart rate and fat expenditure were significantly elevated compared to resting in both sessions' recovery periods; calorie and carbohydrate expenditures were not. Compared to RST, ST represents an equivalent physiological stimulus on key parameters indicative of potential training-induced adaptive responses. Such adaptations could conceivably include cardiovascular conditioning.

Physiological characteristics of international female soccer players.

The purpose of this study was to investigate the physiological characteristics of Fédération Internationale de Football Association (FIFA) eligible international female soccer players aged 14-36 years and to determine if measures were significantly different for players selected (i.e., starters) to the starting line up for an FIFA tournament as compared with those not selected (i.e., nonstarters). Fifty-one (N = 18 Under 17; N = 18 Under 20; N = 15 Senior) international female soccer players participated in this study. The subjects underwent measurements of anthropometry (height and body mass), lower body strength (isokinetic testing), sprint kinetics and kinematics (nonmotorized treadmill), leg power (unilateral jumping), and maximal aerobic velocity (30:15 intermittent fitness test) during the final preparatory stage for an FIFA event. Outcomes of the age group data indicate that differences in physiological capacities are evident for the Under 17 players as compared with those for the Under 20 and Senior capped international players, suggesting a plateau in the acquisition of physical qualities as players mature. Starters tended to be faster (effect size [ES] = 0.55-1.0, p < 0.05) and have a higher maximal aerobic velocity (ES = 0.78-2.45, p < 0.05), along with greater eccentric leg strength (ES = 0.33-1.67, p < 0.05). Significant differences were detected between starters and nonstarters for isokinetic leg strength (ES = 0.54-1.24, p < 0.05) and maximal aerobic velocity (ES = 0.87, p < 0.05) for Under 17 players, where maximal aerobic velocity was the primary difference between starters and nonstarters (ES = 0.83-2.45, p < 0.05) for the Under 20 and Senior players. Coaches should emphasize the development of speed, maximal aerobic velocity, and leg strength in developing female soccer players.

Menstrual cycle patterns and their relationship with measures of well-being and perceived performance metrics in competitive and recreational resistance-trained athletes.

BACKGROUND: There is mixed evidence on how the menstrual cycle (MC) affects sports performance, with many studies showing variations in performance during different phases of the MC, while other evidence shows that the MC's effects on performance may be trivial. Therefore, this exploratory longitudinal monitoring study was designed to investigate MC characteristics and symptoms in a resistance-trained (RT) population to look for associations between measures of well-being and perceived performance metrics across the MC. METHODS: RT females reported their workout habits, perceived performance metrics, and measures of well-being while tracking their MC with detailed methods via daily check-ins in an app. RESULTS: Most MC characteristics and symptoms in the present RT population aligned with previous research on the general population. However, the frequency of irregular cycles was higher than in previous research on the general population. The amount of individual variation and within-subject cycle-to-cycle variation in MC characteristics and MC symptoms was also high. All measures of well-being were significantly associated with specific days of the MC, demonstrating a change in well-being based on the timing of the MC. Several perceived performance metrics were significantly associated with changes across the MC, while others were not. CONCLUSIONS: Overall, with the current evidence as it stands, a highly individualized approach should be taken for any training or performance considerations surrounding the MC due to the high levels of individual variation.

The relative efficacy of three recovery modalities after professional rugby league matches.

This study investigated the relative efficacy of postgame recovery modalities on jump height performance and subjective ratings of muscle soreness and muscle damage at 1, 18, and 42 hours after professional rugby league competition games. Twenty-one professional rugby league players performed 3 different postmatch recovery modalities: cold water immersion (CWI), contrast water therapy (CWT), and active recovery (ACT). The effects of the recovery treatments were analyzed with mixed modeling including a covariate (fatigue score) to adjust for changes in the intensity of each match on the postmatch values of the dependent variables of interest. Standardization of effects was used to make magnitude-based inferences, presented as mean with ±90% confidence limits. Cold water immersion and CWT clearly recovered jump height performance (CWI 2.3 ± 3.7%; CWT 3.5 ± 4.1%), reduced muscle soreness (CWI -0.95 ± 0.37; CWT -0.55 ± 0.37), and decreased creatine kinase (CWI -11.0 ± 15.1%; CWT 18.2 ± 20.1%) by 42 hours postgame compared with ACT. Contrast water therapy was however clearly more effective compared with CWI on the recovery of muscle soreness and creatine kinase by 42 hours postgame. Based on these findings, CWT recovery is recommended postmatch for team rugby sports.

Anaerobic and aerobic fitness profiling of competitive surfers.

Despite widespread popularity of competitive surfing internationally, very little research has investigated the physiological profile of surf athletes and attempted to identify the relationships between physiological measures and surfing performance. This study determined the peak oxygen uptake (V(O2)peak) from an incremental ramp test and anaerobic power (watts) during a 10-second maximal-paddling burst using a surf paddle-specific modified kayak ergometer, customized with a surfboard and hand paddles. Twenty nationally ranked surf athletes volunteered to participate in the VV(O2)peak test, and 8 also participated in the anaerobic power test. The interrelationships between these components of athletic performance and surfing performance, as assessed by season rank, were determined using Pearsons correlations. We found a significant relationship between anaerobic power and season rank (r = 0.55, p = 0.05). No significant relationship between VV(O2)peak and season rank was found (r = -0.02, p = 0.97). Although correlations do not imply cause and effect, such a finding provides theoretical support for the importance of including anaerobic paddling power in assessment batteries and conditioning practice for surf athletes.

Interrelationships between strength, anthropometrics, and strongman performance in novice strongman athletes.

The sport of strongman is relatively new; hence, specific research investigating this sport is currently very limited. The purpose of this study was to determine the relationships between anthropometric dimensions and maximal isoinertial strength to strongman performance in novice strongman athletes. Twenty-three semiprofessional rugby union players with considerable resistance training and some strongman training experience (age 22.0 ± 2.4 years, weight 102.6 ± 10.8 kg, height 184.6 ± 6.5 cm) were assessed for anthropometry (height, body composition, and girth measurements), maximal isoinertial performance (bench press, squat, deadlift, and power clean), and strongman performance (tire flip, log clean, and press, truck pull, and farmer's walk). The magnitudes of the relationships were determined using Pearson correlation coefficients, and interpreted qualitatively according to Hopkins (90% confidence limits ∼±0.37). The highest relationship observed was between system force (body mass + squat 1-repetition maximum) and overall strongman performance (r = 0.87). Clear moderate to very large relationships existed between performance in all strongman events and the squat (r = 0.61-0.85), indicating the importance of maximal squat strength for strongman competitors. Flexed arm girth and calf girth were the strongest anthropometric correlates of overall strongman performance (r = 0.79 and 0.70, respectively). The results of this study suggest that body structure and common gymnasium-based exercise strength are meaningfully related to strongman performance in novice strongman athletes. Future research should investigate these relationships using more experienced strongman athletes and determine the relationships between changes in anthropometry, isoinertial strength, and strongman performance to determine the role of anthropometry and isoinertial strength in the sport of strongman.

Physiological demands of competitive surfing.

This study was a performance analysis of surfing athletes during competitive surfing events in an attempt to inform the development of surfing-specific conditioning. Twelve nationally ranked surfers were fitted with heart rate (HR) monitors and global positioning system (GPS) units and videoed during the heats of 2 sanctioned competitions. Means and SDs represented the centrality and spread of analyzed data. From the 32 videos analyzed, the greatest amount of time spent during surfing was paddling (54 ± 6.3% of the total time) (% TT). The remaining stationary represented 28 ± 6.9% TT, wave riding, and paddling for a wave represented only 8 ± 2% TT and 4 ± 1.5% TT, respectively. Surfers spent 61 ± 7% of the total paddling bouts and 64 ± 6.8% of total stationary bouts between 1 and 10 seconds. The average speed recorded via the GPS for all the subjects was 3.7 ± 0.6 km·h(-1), with an average maximum speed of 33.4 ± 6.5 km·h(-1) (45 km·h(-1) was the highest speed recorded). The average distance covered was 1,605 ± 313 m. The mean HR during the surf competitions was 139 ± 11 b·min(-1) (64% HRmax), with a (mean) peak of 190 ± 12 b·min(-1) (87% HRmax). Sixty percent TT was spent between 56 and 74% of the age-predicted HR maximum (HRmax), 19% TT >46% HRmax, and approximately 3% TT >83% HRmax. Competitive surfing therefore involves intermittent high-intensity bouts of all out paddling intercalated with relatively short recovery periods and repeated bouts of low-intensity paddling, incorporating intermittent breath holding. Surfing-specific conditioning sessions should attempt to replicate such a profile.

Using the load-velocity relationship for 1RM prediction.

The purpose of this study was to investigate the ability of the load-velocity relationship to accurately predict a bench press 1 repetition maximum (1RM). Data from 3 different bench press studies (n = 112) that incorporated both 1RM assessment and submaximal load-velocity profiling were analyzed. Individual regression analysis was performed to determine the theoretical load at zero velocity (LD0). Data from each of the 3 studies were analyzed separately and also presented as overall group mean. Thereafter, correlation analysis provided quantification of the relationships between 1RM and LD0. Practically perfect correlations (r = ∼0.95) were observed in our samples, confirming the ability of the load-velocity profile to accurately predict bench press 1RM.

The strength and conditioning practices of strongman competitors.

This study describes the results of a survey of the strength and conditioning practices of strongman competitors. A 65-item online survey was completed by 167 strongman competitors. The subject group included 83 local, 65 national, and 19 international strongman competitors. The survey comprised 3 main areas of enquiry: (a) exercise selection, (b) training protocols and organization, and (c) strongman event training. The back squat and conventional deadlift were reported as the most commonly used squat and deadlift (65.8 and 88.0%, respectively). Eighty percent of the subjects incorporated some form of periodization in their training. Seventy-four percent of subjects included hypertrophy training, 97% included maximal strength training, and 90% included power training in their training organization. The majority performed speed repetitions with submaximal loads in the squat and deadlift (59.9 and 61.1%, respectively). Fifty-four percent of subjects incorporated lower body plyometrics into their training, and 88% of the strongman competitors reported performing Olympic lifts as part of their strongman training. Seventy-eight percent of subjects reported that the clean was the most performed Olympic lift used in their training. Results revealed that 56 and 38% of the strongman competitors used elastic bands and chains in their training, respectively. The findings demonstrate that strongman competitors incorporate a variety of strength and conditioning practices that are focused on increasing muscular size, and the development of maximal strength and power into their conditioning preparation. The farmers walk, log press, and stones were the most commonly performed strongman exercises used in a general strongman training session by these athletes. These data provide information on the training practices required to compete in the sport of strongman.

Inter-relationships between machine squat-jump strength, force, power and 10 m sprint times in trained sportsmen.

AIM: Strength and conditioning practitioners appear focussed on developing maximal strength based on the premise that it underpins explosive muscular performance. Investigation into the relationship between strength and a multitude of explosive power measures is limited though. Furthermore, the relationship of explosive force and power with functional performance is unclear. METHODS: We examined the inter-relationships between maximal strength and explosive measures of force and power at different loads. Also investigated were the relationships between explosive measures and 10-m sprinting ability. Forty elite-level well-trained rugby union and league athletes performed 10-m sprints followed by bilateral concentric-only machine squat-jumps at 20 and 80%1RM. The magnitudes of the inter-relationships between groups of force measures, power measures and sprint times were interpreted using Pearson correlation coefficients, which had uncertainty (90% confidence limits) of approximately +/-0.25. Measures investigated included peak force, peak power, rate of force development, and some of Zatsiorsky's explosive measures, all expressed relative to body mass. RESULTS: The relationship between maximal strength and peak power was moderate at 20 %1RM (r=0.32) but trivial at 80 %1RM (r=-0.03). Practically no relationship between any of the explosive measures and 10-m sprint ability was observed (r=-0.01 to 0.06). CONCLUSION: Although correlations do not imply cause and effect, we speculate that the common practice of focussing on high levels of maximal strength in a machine squat to improve power output may be misguided. Our results also cast doubt on the efficacy of increasing explosive force and power in a machine squat-jump with the intention of improving sprint ability in well-trained athletes.

Incidence of V˙O2max Responders to Personalized versus Standardized Exercise Prescription.

INTRODUCTION: Despite knowledge of cardiorespiratory fitness (CRF) training responders and nonresponders, it is not well understood how the exercise intensity prescription affects the incidence of response. The purpose of this study was to determine CRF training responsiveness based on cohort-specific technical error after 12 wk of standardized or individually prescribed exercise and the use of a verification protocol to confirm maximal oxygen uptake (V˙O2max). METHODS: Sedentary adult participants (9 men, 30 women; 48.2 ± 12.2 yr) completed exercise training on 3 d·wk for 12 wk, with exercise intensity prescribed based on standardized methods using heart rate reserve or an individualized approach using ventilatory thresholds. A verification protocol was used at baseline and 12 wk to confirm the identification of a true V˙O2max and subsequent relative percent changes to quantify CRF training responsiveness. A cohort-specific technical error (4.7%) was used as a threshold to identify incidence of response. RESULTS: Relative V˙O2max significantly increased (P < 0.05) from 24.3 ± 4.6 to 26.0 ± 4.2 and 29.2 ± 7.5 to 32.8 ± 8.6 mL·kg·min for the standardized and individualized groups, respectively. Absolute V˙O2max significantly increased (P < 0.05) from 2.0 ± 0.6 to 2.2 ± 0.6 and 2.4 ± 0.8 to 2.6 ± 0.9 L·min for the standardized and individualized groups, respectively. A significant difference in responsiveness was found between the individualized and standardized groups with 100% and 60% of participants categorized as responders, respectively. CONCLUSIONS: A threshold model for exercise intensity prescription had a greater effect on the incidence of CRF training response compared with a standardized approach using heart rate reserve. The use of thresholds for intensity markers accounts for individual metabolic characteristics and should be considered as a viable and practical method to prescribe exercise intensity.

Squat jump training at maximal power loads vs. heavy loads: effect on sprint ability.

Training at a load maximizing power output (Pmax) is an intuitively appealing strategy for enhancement of performance that has received little research attention. In this study we identified each subject's Pmax for an isoinertial resistance training exercise used for testing and training, and then we related the changes in strength to changes in sprint performance. The subjects were 18 well-trained rugby league players randomized to two equal-volume training groups for a 7-week period of squat jump training with heavy loads (80% 1RM) or with individually determined Pmax loads (20.0-43.5% 1RM). Performance measures were 1RM strength, maximal power at 55% of pretraining 1RM, and sprint times for 10 and 30 m. Percent changes were standardized to make magnitude-based inferences. Relationships between changes in these variables were expressed as correlations. Sprint times for 10 m showed improvements in the 80% 1RM group (-2.9 +/- 3.2%) and Pmax group (-1.3 +/- 2.2%), and there were similar improvements in 30-m sprint time (-1.9 +/- 2.8 and -1.2 +/- 2.0%, respectively). Differences in the improvements in sprint time between groups were unclear, but improvement in 1RM strength in the 80% 1RM group (15 +/- 9%) was possibly substantially greater than in the Pmax group (11 +/- 8%). Small-moderate negative correlations between change in 1RM and change in sprint time (r approximately -0.30) in the combined groups provided the only evidence of adaptive associations between strength and power outputs, and sprint performance. In conclusion, it seems that training at the load that maximizes individual peak power output for this exercise with a sample of professional team sport athletes was no more effective for improving sprint ability than training at heavy loads, and the changes in power output were not usefully related to changes in sprint ability.

Relationship between sprint times and the strength/power outputs of a machine squat jump.

Strength testing is often used with team-sport athletes, but some measures of strength may have limited prognostic/diagnostic value in terms of the physical demands of the sport. The purpose of this study was to investigate relationships between sprint ability and the kinetic and kinematic outputs of a machine squat jump. Thirty elite level rugby union and league athletes with an extensive resistance-training background performed bilateral concentric-only machine squat jumps across loads of 20% to 90% 1 repetition maximum (1RM), and sprints over 10 meters and 30 or 40 meters. The magnitudes of the relationships were interpreted using Pearson correlation coefficients, which had uncertainty (90% confidence limits) of approximately +/-0.3. Correlations of 10-meter sprint time with kinetic and kinematic variables (force, velocity, power, and impulse) were generally positive and of moderate to strong magnitude (r = 0.32-0.53). The only negative correlations observed were for work, although the magnitude was small (r = -0.18 to -0.26). The correlations for 30- or 40-meter sprint times were similar to those for 10-meter times, although the correlation with work was positive and moderate (r = 0.35-0.40). Correlations of 10-meter time with kinetic variables expressed relative to body mass were generally positive and of trivial to small magnitude (r = 0.01-0.29), with the exceptions of work (r = -0.31 to -0.34), and impulse (r = -0.34 to -0.39). Similar correlations were observed for 30- and 40-meter times with kinetic measures expressed relative to body mass. Although correlations do not imply cause and effect, the preoccupation with maximizing power output in this particular resistance exercise to improve sprint ability appears problematic. Work and impulse are potentially important strength qualities to develop in the pursuit of improved sprinting performance.

Acute blood glucose, cardiovascular and exaggerated responses to HIIT and moderate-intensity continuous training in men with type 2 diabetes mellitus.

BACKGROUND: Optimizing exercise-induced physiological responses without increasing the risk of negative exaggerated responses is an important aspect of exercise prescription for people with type 2 diabetes mellitus (T2DM). However, knowledge of acute responses, including exaggerated responses, of different training modalities is limited. The aim of the study was to compare acute physiological responses of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) in T2DM. METHODS: Baseline data were used to randomly assign male participants into supervised training groups for a 12-week intervention. During week 7, participants trialed either a fully progressed MICT (N.=11) or HIIT (N.=11) (combined with resistance training) session. The MICT included 26 minutes at 55% estimated maximum workload (eWLmax) while the HIIT included twelve 1-minute bouts at 95% eWLmax interspersed with 1-minute bouts at 40% eWLmax. RESULTS: While energy expenditure and peak systolic and diastolic blood pressure responses were similar between groups (P=0.47, P=0.71, P=0.56, respectively), peak heart rate, workload and perceived exertion were higher in the HIIT group (P=0.04, P<0.001, and P<0.001, respectively). Acute exaggerated responses were similar (P=0.39) for MICT (64%) and HIIT (36%) participants. CONCLUSIONS: While structured MICT and HIIT sessions resulted in comparable acute physiological responses, the individual variations and exaggerated responses, even after preparatory training, necessitated precautionary respite in T2DM men.

High-Intensity Interval Training Is Equivalent to Moderate-Intensity Continuous Training for Short- and Medium-Term Outcomes of Glucose Control, Cardiometabolic Risk, and Microvascular Complication Markers in Men With Type 2 Diabetes.

We sought to determine the efficacy of 12 weeks high-intensity interval training (HIIT), compared to moderate-intensity continuous training (MICT) on glucose control, cardiometabolic risk and microvascular complication markers in men living with type 2 diabetes (T2D). Both modalities were combined with resistance training (RT). Additionally, the study aimed to determine the medium-term durability of effects. After a 12-week, thrice weekly, training intervention incorporating either MICT+RT (n = 11) or HIIT+RT (n = 12), the study concluded with a 6-month follow-up analysis. The middle-aged study participants were obese, had moderate duration T2D and were taking multiple medications including insulin, statins and beta-blockers. Participants, randomized via the method of minimization, performed MICT (progressing to 26-min at 55% maximum estimated workload [eWLmax]) or HIIT (progressing to two variations in which twelve 1-min bouts at 95% eWLmax interspersed with 1-min recovery bouts, alternated with eight 30-s bouts at 120% eWLmax interspersed with 2:15 min recovery bouts) under supervision at an exercise physiology facility. To account for fixed and random effects within the study sample, mixed-effect models were used to determine the significance of change following the intervention and follow-up phases and to evaluate group*time interactions. Beyond improvements in aerobic capacity (P < 0.001) for both groups, both training modalities elicited similar group*time interactions (P > 0.05) while experiencing benefits for glycated hemoglobin (HbA1c; P = 0.01), subcutaneous adiposity (P < 0.001), and heart rate variability (P = 0.02) during the 12-week intervention. Adiposity (P < 0.001) and aerobic capacity (P < 0.001) were significantly maintained in both groups at the 6-month follow-up. In addition, during the intervention, participants in both MICT+RT and HIIT+RT experienced favorable reductions in their medication usage. The study reported the inter-individual variability of change within both groups, the exaggerated acute physiological responses (using exercise termination indicators) that occurred during the interventions as well as the incidence of precautionary respite afforded in such a study sample. To reduce hyperglycaemia, and prevent further deterioration of cardiometabolic risk and microvascular complication markers (in both the short- and medium-term), future strategies that integrate the adoption and maintenance of physical activity as a cornerstone in the treatment of T2M for men should (cognisant of appropriate supervision) include either structured MICT+RT, or HIIT+RT. Clinical Trials Registration Number: ACTRN12617000582358 http://www.anzctr.org.au/default.aspx.