High-intensity Functional Training Session Research Articles

High intensity functional training for people with spinal cord injury & their care partners.

Non-randomized clinical trial. Examine the feasibility, physical and psychosocial effects of a high intensity functional training (HIFT) exercise program for people with spinal cord injury (pSCI) and their care partners (CPs). Community fitness center in a Medically Underserved Area (Fort Smith, USA.) METHODS: A single-group design with three assessment points (before the program, at midpoint (13 weeks), and post-program (25 weeks) was used to examine the effects of up to 49 HIFT sessions over 25-weeks. Sessions were 60 to 75 min in duration and adapted to the abilities of participants. Feasibility measures included recruitment, retention, attendance, safety and fidelity (exercise intensity rated via session-Rating of Perceived Exertion (RPE). Physical measures included cardiovascular endurance, anaerobic power, and muscular strength. Psychosocial measures included perceived social support for exercise, exercise self-efficacy and health-related quality of life. Fourteen pSCI (7 with paraplegia and 7 with tetraplegia, 2 females) and 6 CPs (4 females) were included (median age = 60) (IQR = 15.8). Recruitment rates were 40% for pSCI and 32% for CPs. On average, participants attended 73% (22%) of exercise sessions with a median session-RPE of 5 (IQR = 1). Retention rates were 83% and 67% for pSCI and CPs, respectively. For pSCI and their CPs, large effect sizes were observed for cardiovascular endurance, anaerobic power, muscular strength, and social support for exercise. For pSCI and their CPs, HIFT appears feasible and potentially leads to improvements in physical and psychosocial health for both groups.

Unlocking the power of synergy: High-intensity functional training and early time-restricted eating for transformative changes in body composition and cardiometabolic health in inactive women with obesity.

The purpose of this study was to examine the long-term effects of time-restricted eating (TRE), with or without high intensity functional training (HIFT), on body composition and cardiometabolic biomarkers among inactive women with obesity. Sixty-four women (BMI = 35.03 ± 3.8 kg/m2; age = 32.1 ± 10 years) were randomly allocated to either: (1) TRE (≤8-h daily eating window, with ad libitum energy intake) group; (2) HIFT (3 sessions/week) group; or (3) TRE combined with HIFT (TRE-HIFT) group. The interventions lasted 12 weeks with a pre-post measurement design. A HIFT session consists of 8 sets of multiple functional exercises with self-selected intensity (20 or 30s work/10s rest). TRE-HIFT showed a greater decrease of waist and hip circumferences and fat mass compared to TRE (p = 0.02, p = 0.02 and p<0.01; respectively) and HIFT (p = 0.012, p = 0.028 and p<0.001; respectively). Weight and BMI decreased in TRE-HIFT compared to HIFT group (p<0.001; for both). Fat-free mass was lower in TRE compared to both HIFT and TRE-HIFT groups (p<0.01 and p<0.001; respectively). Total cholesterol, triglyceride, insulin, and HOMA-IR decreased in TRE-HIFT compared to both TRE (p<0.001, p<0.01, p = 0.015 and p<0.01; respectively) and HIFT (p<0.001, p = 0.02, p<0.01 and p<0.001; respectively) groups. Glucose level decreased in TRE-HIFT compared to HIFT (p<0.01). Systolic blood pressure decreased significantly in both TRE-HIFT and HIFT groups compared to TRE group (p = 0.04 and p = 0.02; respectively). In inactive women with obesity, combining TRE with HIFT can be a good strategy to induce superior effects on body composition, lipid profile and glucose regulation compared with either diet or exercise intervention alone. Clinical Trials Number: PACTR202301674821174.

Comparison of physiological and psychobiological acute responses between high intensity functional training and high intensity continuous training

Little is known about the physiological and psychobiological responses that occur during and after high intensity functional training (HIFT). We compared physiological and psychobiological responses during and after a HIFT session with a high intensity continuous training (HICT) session. Twenty-one trained and healthy men were submitted to 20-min session of HIFT and HICT on separate days. The heart rate, blood lactate concentration [Lac], levels of state anxiety, rates of perceived exertion (RPE) and perceived discomfort (RPE-D), and affective valence were measured. Exercise intensity of the HICT was adjusted to the mean heart rate obtained in the HIFT session. The highest heart rate in the training sessions was significantly higher in HIFT (mean ​± ​standard deviation [SD]: [187 ​± ​9] bpm) than in HICT (mean ​± ​SD: [178 ​± ​8] bpm, p ​< ​0.001). The [Lac] was significantly higher immediately after the HIFT (median [interquartile range (IQR)]: 6.8 [4.4] mmol/L) than the HICT (median [IQR]: 3.2 [1.9], p ​= ​0.021) and 10 ​min after (median [IQR]: HIFT ​= ​6.8 [4.9] mmol/L, HICT ​= ​2.9 [2.4] mmol/L, p ​= ​0.003). The RPE was also significantly higher in the HIFT (median [IQR]: HIFT ​= ​20 [2], HICT ​= ​15 [5], p ​= ​0.009). The physiological and psychobiological responses compared between HIFT and HICT sessions are similar, except for the higher heart rate obtained during the sessions, [Lac] and RPE. Probably, the results found for the higher heart rate obtained during the sessions, [Lac] and RPE may be explained by the higher participation of the anaerobic glycolytic metabolism during the HIFT session.

The effects of high-intensity functional training on muscle damage and recovery capacity in trained individuals

Objective: High-Intensity Functional Training (HIFT) is nowadays widely used due to low time demand and efficiency to improve performance and health. The dynamics of recovery of muscle damage and physical fitness after a HIFT in individuals with different fitness status provide a practical information for coaches and practitioners. Therefore, the aim of this study was to verify the muscle damage and performance recovery responses after an acute HIFT session in healthy young men with different fitness status.Method: Sixteen recreationally trained participants (age: 23.4 ± 2.4 y; body mass index: 24.6 ± 2.4 kg·m-2; 1RM back squat: 120.1 ± 19.9 kg) were divided into two groups according to their maximum strength (higher-trained [HT] and lower-trained group [LT]), and performed a single HIFT session. Muscle damage (creatine kinase [CK] and lactate dehydrogenase [LDH]) and physical fitness tests (strength, power, and oxygen consumption) were analyzed before, immediately after, 24h and 48h after the HIFT session. The internal training load for both groups was equalized using the Rating of Perceived Exertion method (RPE) and the percentage 1 repetition maximum (1RM).Results: Biochemical markers and performance indicators showed that both groups suffered exercise-induced muscle damage. There was a trend towards faster muscle damage recovery in HT group.Conclusions: HT group showed higher muscle damage recovery compared to the LT group. A longer recovery time to complete muscle recovery might be expected in the LT group.

High-Intensity Functional Training: Perceived Functional and Psychosocial Health-Related Outcomes from Current Participants with Mobility-Related Disabilities.

People with mobility-related disabilities (MRDs) experience many personal and environmental barriers to engagement in community-based exercise programs. We explored the experiences of adults with MRD who currently participate in high-intensity functional training (HIFT), an inclusive and accessible community-based exercise program. Thirty-eight participants completed online surveys with open-ended questions, with ten individuals also participating in semi-structured interviews via telephone with project PI. Surveys and interviews were designed to examine changes to perceived health, and the elements of HIFT that promote sustained participation. Thematic analysis revealed themes related to health changes following HIFT participation including improved physical, functional, and psychosocial health outcomes. Other themes emerged within the HIFT environment that promoted adherence for participants such as accessible spaces and equipment, and inclusive HIFT sessions and competitions. Additional themes included participants' advice for the disability and healthcare communities. The resulting themes are informed by the World Health Organization's International Classification of Functioning, Disability, and Health. The findings provide initial data on the potential effects of HIFT on multiple dimensions of health outcomes and contribute to the growing literature on community-based programs that are adaptable and inclusive for people with MRD.

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.

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.

Comparison of Different Recovery Strategies After High-Intensity Functional Training: A Crossover Randomized Controlled Trial.

We aimed to determine whether voluntary exercise or surface neuromuscular electrical stimulation (NMES) could enhance recovery after a high-intensity functional training (HIFT) session compared with total rest. The study followed a crossover design. Fifteen male recreational CrossFit athletes (29 ± 8 years) performed a HIFT session and were randomized to recover for 15 min with either low-intensity leg pedaling (“Exercise”), NMES to the lower limbs (“NMES”), or total rest (“Control”). Perceptual [rating of perceived exertion (RPE) and delayed-onset muscle soreness (DOMS) of the lower-limb muscles], physiological (heart rate, blood lactate and muscle oxygen saturation) and performance (jump ability) indicators of recovery were assessed at baseline and at different time points during recovery up to 24 h post-exercise. A significant interaction effect was found for RPE (p = 0.035), and although post hoc analyses revealed no significant differences across conditions, there was a quasi-significant (p = 0.061) trend toward a lower RPE with NMES compared with Control immediately after the 15-min recovery. No significant interaction effect was found for the remainder of outcomes (all p > 0.05). Except for a trend toward an improved perceived recovery with NMES compared with Control, low-intensity exercise, NMES, and total rest seem to promote a comparable recovery after a HIFT session.

Acute leucocyte, muscle damage, and stress marker responses to high-intensity functional training.

High-intensity functional training (HIFT) has become more popular, and the number of practitioners has increased; however, it remains unclear whether perturbations in the immune parameters occur, even after one single bout. Our aim was to examine acute leucocyte, muscle damage, and stress marker responses following a single 'Cindy' workout session, and compare the results between novice and experienced participants. Twenty-three HIFT practitioners (age 31.0 ± 1.0 years) completed the 'Cindy' workout. They were categorized as novice (3-8 months of experience; n = 10) and experienced (≥18 months; n = 13). White blood cell (WBC) count, plasma creatine kinase (CK) activity, blood cortisol level, and lactate concentration were measured. Blood analysis was performed before (pre-ex), immediately after (post-ex), 30 min after (post-30 min), and 24 h after (post-24 h) a single 'Cindy' workout session. WBC count was higher post-ex (6.8 to 11.8x103/μL) and returned to baseline values within post-30 min (p<0.01). Neutrophil (3.3 to 4.5x103/μL) and lymphocyte levels (2.8 to 5.9x103/μL) were higher post-ex and returned to baseline values after post-24 h, yet lymphocytopoenia (2.2x103/μL) was observed at post-30 min (p<0.01). CK increased post-ex (174.9 to 226.7 U.L-1) and remained elevated post-24 h. Cortisol (14.7 to 17.0 μg/dL) and lactate (1.9 to 13.5 mmol.l-1) responses increased post-ex, but only the lactate level was reduced at post-30 min (p<0.01). The experienced participants had higher WBC, lymphocyte, and cortisol concentrations post-ex than the novice ones (p<0.01). A single HIFT session elicited significant acute perturbations in WBC count, stress markers, and muscle tissue, which is like other similar regimens. Importantly, the experienced participants showed greater lymphocyte and cortisol responses than the novice ones.

High-Intensity Functional Training Shows Promise for Improving Physical Functioning and Activity in Community-Dwelling Older Adults: A Pilot Study.

Healthy aging allows older adults to remain active in their communities; however, sedentary behaviors can lead to physical deconditioning and decreased physical function. Structured exercise programs are recommended to facilitate activity engagement and prevent muscle atrophy due to aging to facilitate older adults' abilities to complete activities of daily living. In particular, high-intensity functional training (HIFT) is a multicomponent group exercise program that has previously been shown to increase physical function for middle-age cancer survivors. This study examined the preliminary feasibility and effectiveness of HIFT for improving physical function and participation in physical activity for community-dwelling older adults. The 8-week pilot study included two 60-minute HIFT sessions per week. Participants (n = 8) were 75% female with a mean age of 71 (6) years. Study initiation, adherence, and acceptability were assessed to determine feasibility. Effectiveness was assessed via 5 physical function measures conducted during sessions 1 and 16 and included the Timed Up and Go, lift and carry test, chair stand test, a repeated stair climb test, and the 6-minute walk test. Participants also self-reported confidence and difficulty for activities of daily living via the Outpatient Physical Therapy Improvement in Movement Assessment Log and physical activity participation via the Community Health Activities Model Program for Seniors questionnaire. The study recruitment rate was 88.9% and 87.5% of participants adhered. Intervention acceptability was promising, as 4 participants reported liking multiple aspects of the intervention (eg, coaching/supervision and similar age peers). Intervention effectiveness was promising with significant improvement in 1 of 5 physical function measures, although clinical effects were most likely trivial. Participants reported increased participation in both leisure and structured physical activities. HIFT appeared feasible and showed promise for counteracting the loss of physical function and sedentary behaviors associated with aging. Results should be confirmed in a longer, fully powered study.

Effects of Caffeine on High-Intensity Functional Training Performance

Caffeine demonstrates an ergogenic effect on endurance exercise performance, however, limited information exists establishing its efficacy during high-intensity functional training (HIFT). HIFT is an exercise program that incorporates a variety of multi-joint movements performed at a relatively high-intensity and designed to improve parameters of general physical fitness and performance. PURPOSE: Our study aimed to determine the effects of caffeine on HIFT performance. METHODS: 13 HIFT-trained men (age = 28.5 ± 6.6 years, HIFT experience = 4.1 ± 3.0 years, body weight= 84.3 ± 9.9 kg) were randomized in a double-blind, crossover design. After consent, participants completed two HIFT sessions separated by a 7-day washout period, 60-minutes after consuming 5mg/kg of caffeine or a placebo. During HIFT sessions, participants completed as-many-rounds-as-possible in 20 minutes of 5 pull-ups, 10 push-ups, and 15 air squats, with performance measured as the number of rounds completed (30 repetitions = 1 round). Paired-samples t-tests were used to compare HIFT performance between the caffeine and placebo conditions and to test for a potential learning effect between the first and second sessions. RESULTS: Participants significantly improved HIFT performance during the caffeine trial (15.3 ± 3.6 rounds) as compared to placebo (14.3 ± 3.0 rounds), t(12) = -2.783, p < 0.05. The eta squared statistic (0.39) indicated a large effect size. Moreover, no significant learning effect was identified between the first and second sessions (14.9 ± 3.2 vs. 14.7 ± 3.5 rounds, p = 0.73). CONCLUSION: Caffeine elicited an ergogenic response during HIFT in HIFT-trained men, with no identifiable learning effect, which is useful for competitive HIFT athletes aiming to optimize performance. However, future investigations should establish the efficacy of caffeine during varying-duration HIFT sessions and among female HIFT athletes.

Energy Expenditure and Intensity of Group-Based High-Intensity Functional Training: A Brief Report.

High-intensity functional training (HIFT) may offer an attractive, time-efficient alternative to traditional aerobic exercise. However, limited information is available in the literature regarding HIFT meeting exercise guidelines for energy expenditure (improve health outcomes: ≥1000kcal/wk; weight management: ≥2000kcal/wk) and level of intensity (moderate: 3-6 metabolic equivalents [METs], vigorous: ≥6 METs) elicited by this approach. Thus, the primary aim was to objectively measure energy expenditure and intensity of HIFT sessions. \Energy expenditure was assessed in 20 adults (18-50y, 50% females). The HIFT session format included the following segments: warm-up (∼5min), exercise (∼35min), and cooldown (∼5min). Participant oxygen consumption (COSMED, L/min and mL/kg/min), heart rate (Polar RS400), and physical activity (ActiGraph GT3X+) were collected in 15-second intervals. Average kcal per minute, METs, total kcal per session, and percent maximum heart rate (HRmax) were calculated. METs ranged from 5.5 to 11.6 for the complete session (including warm-up and cooldown). Participant's HRmax was ∼80% (range: 69%-100%). Average energy expenditure was ∼485kcal per session (∼1400kcal/wk). The vigorous-intensity exercise portion (∼35min) contributed to 80% of total energy expenditure. HIFT has the potential to meet the recommendations for exercise to improve health outcomes.

The Multimodal Nature of High-Intensity Functional Training: Potential Applications to Improve Sport Performance

Training for sports performance requires the development of multiple fitness components within the same program. In this context, training strategies that have the potential to concomitantly enhance metabolic and musculoskeletal fitness are of great value for athletes and coaches. The purpose of this manuscript is to review the current studies on high-intensity functional training (HIFT) and to assess how HIFT could be utilized in order to improve sport-specific performance. Studies on untrained and recreationally-active participants have led to positive results on aerobic power and anaerobic capacity, and muscular endurance, while results on muscular strength and power are less clear. Still, HIFT sessions can elicit high levels of metabolic stress and resistance training exercises are prescribed with parameters that can lead to improvements in muscular endurance, hypertrophy, strength, and power. As similar training interventions have been shown to be effective in the athletic population, it is possible that HIFT could be a time-efficient training intervention that can positively impact athletes’ performances. While the potential for improvements in fitness and performance with HIFT is promising, there is a clear need for controlled studies that employ this training strategy in athletes in order to assess its effectiveness in this population.

Acute inflammatory responses to high-intensity functional training programming: An observational study

Effects of varying types of short duration workouts in high-intensity functional training (HIFT) on inflammatory biomarkers have not been adequately characterized. Objectives: The purpose of this descriptive study was to examine the acute effects of HIFT workouts on biomarkers of inflammation, over time, in two HIFT bouts. Materials and Methods: Ten apparently healthy males (28.1 ± 5 yrs) completed two HIFT sessions (“short bout:” sub-5-minute vs. “long bout:” 15-minute) in a randomized crossover design. Blood was drawn pre and post-exercise, and 1 hour, 3 hours, and 6 hours post-exercise, centrifuged, and plasma frozen for analysis. Inflammation was assessed through plasma interleukin-6 (IL-6), interleukin-10 (IL-10), and tumour necrosis factor alpha (TNF-α). Results: Repeated measures ANOVA revealed a single trial-dependent difference (IL-6, p≤ 0.05), and while statistically significant, this difference may not be biologically significant. The biomarkers IL-6, IL-10, and TNF-α all follow a similar pattern of peaking post-exercise and returning to baseline within 6 hours in both trials. Conclusions: Both temporal responses and concentrations were similar in the short and long bout. A practical implication is that both bouts of a HIFT elicit certain specific physiologic inflammatory responses.

The use of a smart-textile garment during high-intensity functional training: a pilot study.

Wearable devices are common in the health and fitness industry and provide valuable information to improve and achieve fitness goals. The Hexoskin shirt (Hx) is one such device that has been shown to be valid and reliable. The purpose of this pilot study was to compare the Hx to established methods during a maximal graded exercise test (TM) and a high-intensity functional training (HIFT) session. Ten healthy individuals (31.0±7.6 years, 76.4±11.4 kg; 1.7±0.1 m) volunteered for this study and completed a TM and a HIFT exercise session. During both testing sessions, respiratory measures (respiratory rate [RR], and respiratory volume [RV]) were assessed using a portable metabolic system (Cosmed K4b2; K4), and heart rate (HR) was determined via ECG in a standard 12-lead configuration. The Hx was worn during both sessions. During TM, a 4% difference was noted for HR during cool down, while exercising HR and RV, along with RR during cool down were all under 10%. During HIFT, HR at rest and cool down, as well as RR during exercise were less than 10%. The variation between technologies for the remaining variables ranged between 12.3-39.9% and 10.9-41.1% for TM and HIFT, respectively. The Hx smart garment may be utilized to provide select cardiorespiratory data in a TM and HIFT session. We recommend that the validity and reliability be fully established before the Hx smart garment is entirely utilized for all cardiorespiratory data and research purposes in a field-based environment.

Autonomic response to a short and long bout of high-intensity functional training

ABSTRACTThe evaluation of Autonomic Nervous System (ANS) recovery following exercise provides insight into the transient stress placed on the cardiovascular system. High-Intensity Functional Training (HIFT) is a form of intense exercise that is prescribed in various modalities and durations; however, little is known about the influence of HIFT duration on ANS recovery. Ten apparently healthy males (28.1 ± 5.4 yrs) performed two HIFT sessions (<5-minute and 15-minute) in a crossover fashion. ANS activity was measured using plasma Epinephrine (E) and Norepineprine (NE); Heart Rate Variability markers of the log transformed Root Mean Square of Successive Differences (lnRMSSD) and High-Frequency power (lnHF). No trial dependent differences were observed in lnRMSSD (p = 0.822), lnHF (p = 0.886), E (p = 0.078), or NE (p = 0.194). A significant main time effect was observed in both trials with a depression in lnRMSSD and lnHF following the trials (p < 0.05) and recovering by 2-hours post (p = 0.141, p > 0.999) respectively. A trial dependent increase in E and NE occurred immediately post (p < 0.05) and recovered by 1-hour post (p > 0.999, p > 0.999) respectively. The HIFT bouts examined within this study demonstrated similar transient strain of the ANS.

Heart Rate Variability Following a Short and Long Bout of High-Intensity Functional Training

Depression of Heart Rate Variability (HRV) occurs following exercise and is influenced by the intensity and duration of the activity. High-Intensity Functional Training (HIFT) is a style of training performed using various modalities and durations. PURPOSE: To examine the effect of a short (<5-min) and a long (15-min) bout of HIFT on HRV recovery. METHODS: Ten apparently healthy males (28 ± 5 yrs) participated in this study. Two HIFT sessions were performed in a crossover fashion. Each visit consisted of three HRV recordings: at rest (PRE; 10-min), post exercise (P; 45-min), and two-hours post (P2HR; 10-min). The short bout (SHORT) consisted of 30 power clean-and-jerks (61 kg) for time, while the long bout (LONG) was a 15-min circuit of 250m row, 20 kettlebell swings (24 kg), and 15 dumbbell squat presses (16 kg). The HRV marker used was the Root Mean Square of Successive Differences (RMSSD) and was analyzed in 5-min segments: the last 5-minutes of PRE, eight segments during P (P1-P8) starting at the 5th minute, and the last 5-mins of P2HR. RESULTS: Normality was violated and data underwent a natural log transformation (lnRMSSD). Repeated Measures ANOVA did not reveal any significant differences in lnRMSSD between the SHORT and LONG trials (p = 0.822). A significant time effect (p = 0.023) was observed in both trials, with lnRMSSD depression occurring from P1-P8 (p < 0.05) and recovering by P2HR (p = 0.141). CONCLUSION: This study indicates that SHORT and LONG bouts of HIFT result in similar HRV depression and recovery. Future research is needed to better understand various bouts of HIFT and its relationship with HRV.

Oxygen Uptake during Three Varying Duration High-Intensity Functional Training Sessions

Oxygen Uptake during Three Varying Duration High-Intensity Functional Training Sessions