High intensity interval training does not impair strength gains in response to resistance training in premenopausal women

Physiological and Anthropometric Differences Among Endurance, Strength, and High-Intensity Functional Training Participants: A Cross-Sectional Study

Purpose: We compared aerobic capacity (V˙O2max), mitochondrial capacity (mV˙O2), anaerobic power, strength, and muscle endurance in healthy, active men from strength (STR), endurance (END) and high-intensity functional training (HIFT) backgrounds. Methods: Twenty-four men (n = 8/group) completed a cycle ergometer test to determine V˙O2max, followed by a 3-min all-out test to determine peak (PP) and end power (EP), and to estimate anaerobic [work done above EP (WEP)] and aerobic work capacity. Strength was determined by knee extensor maximal voluntary contraction at various flexion angles. The endurance index (EI) of the vastus lateralis (VL) was assessed by measuring muscle contraction acceleration during electrical twitch mechanomyography. mV˙O2max of the VL was assessed using near-infrared spectroscopy to estimate muscle oxygen consumption during transient femoral artery occlusions. Results: V˙O2max was significantly different among groups (p < .05). PP was significantly higher in HIFT and STR versus END (p < .05). EP was significantly higher in HIFT and END compared to STR (p < .05). WEP was significantly higher in STR compared to END (p < .05), whereas total work done was significantly higher in HIFT and END compared to STR (p < .05). mV˙O2max and EI were comparable between HIFT and END but significantly lower in STR versus END (p < .05). Torque production was significantly lower in END compared to STR and HIFT at all flexion angles (p < .05), with no difference between STR and HIFT. Conclusion: HIFT participants can exert similar power outputs and absolute strength compared to strength focused participants but exhibit fatigue resistance and mitochondrial capacity comparable to those who train for endurance.

Muscle strength gains per week are higher in the lower-body than the upper-body in resistance training experienced healthy young women-A systematic review with meta-analysis

BACKGROUND

Women are underrepresented in resistance exercise-related studies. To date only one meta-analysis provides concrete training recommendations for muscle strength gains through resistance training in eumenorrhoeic women.

OBJECTIVE

This review aims to identify research gaps to advance future study in this area to expand the knowledge concerning resistance exercise-induced strength gains in women and to provide guidelines on the number of repetitions per set and the training frequency per week to enhance maximal muscle strength.

METHODS

The electronic databases PubMed and Web of Science were searched using a comprehensive list of relevant terms. After checking for exclusion criteria, 31 studies could be included in the final analysis using data from 621 subjects. From these data sets, the ideal number of repetitions per set and also the training frequency per week were analyzed.

RESULTS

In the lower body, the largest gains were achieved with 1 to 6 repetitions (17.4% 1RM increase). For lower-body exercises, the highest gains were achieved with 13 to 20 repetitions (8.7% 1RM increase). The lower body should be trained two times a week (8.5% 1RM increase). The upper body should be trained two (5.2% 1RM increase) to three times (4.5% 1RM increase) a week.

CONCLUSION

Women can increase their 1RM by 7.2% per week in the upper body and by 5.2% per week in the lower-body exercises. The upper body can be trained more than two times per week whereas the lower body should be trained two times. Women with intermediate experiences in RT and advanced performance level show more rapid increases in strength in the lower-body compared to the upper-body while no differences were found between upper and lower limb adaptations in RT-beginner subjects.

HIIT, RESISTANCE TRAINING, AND RISK FACTORS IN ADOLESCENTS: A SYSTEMATIC REVIEW

ABSTRACT It has been shown that combined physical exercise is an efficient non-pharmacological approach in the context of public health, since it has demonstrated satisfactory results in the prevention, treatment and control of various morbidities. Therefore, it is essential to systematize current knowledge to enable professionals involved in the prescription of physical exercise to do so based on evidence. Thus, the objective of this study was to perform a systematic review of randomized clinical trials to verify changes in cardiometabolic risk factors induced by high-intensity interval training (HIIT) and resistance training (RT) in adolescents. The systematic search was performed in the following databases: Pubmed, ScienceDirect, Cochrane, LILACS and Scielo. Initially 933 studies were identified, then two researchers eliminated duplications and manuscripts that did not meet the eligibility criteria. Thus, two articles were included that met these criteria: a randomized clinical trial conducted with adolescents (10 to 19 years) of both sexes, an intervention lasting for at least four weeks, which prescribed HIIT and RT in the same session or not, and evaluation of at least one cardiometabolic risk factor. The results demonstrated that eight to 12 weeks of HIIT and RT without nutritional intervention were effective in significantly reducing waist circumference and body fat percentage. However, data pertinent to the efficacy of this combination on risk of developing type 2 diabetes mellitus and arterial hypertension are controversial. In view of the above, it is ascertained from the included studies that the combination of HIIT and RT has the potential to reduce cardiometabolic risk factors in adolescents; therefore, further studies should be conducted to determine the effectiveness of this prescription of physical exercise. Level of Evidence II; Systematic review of Level II or Level I Studies with discrepant results.

Effects of 2 Methods of Combined Training on Cardiometabolic Risk Factors in Adolescents: A Randomized Controlled Trial

PURPOSE

To analyze the effects of 2 combined training methods on the cardiometabolic risk factors in adolescents.

METHODS

A total of 76 adolescents (16.1 [1.1] y, n = 44 female) were randomized into groups of moderate-intensity continuous training combined with resistance training (MICT + RT), high-intensity interval training combined with resistance training (HIIT + RT), or control. The training sessions were performed twice weekly for 12 weeks. The outcomes evaluated included body fat percentage, waist circumference, fasting blood glucose, fasting insulin, total cholesterol, triglycerides, low-density lipoprotein, high-density lipoprotein, glycated hemoglobin, insulin resistance index, blood pressure, peak oxygen consumption (VO2peak), and cardiometabolic risk Z score.

RESULTS

The intervention groups presented a significant reduction in the cardiometabolic risk Z score after 12 weeks of the combined exercise program. In relation to the cardiometabolic risk Z score between groups, the HIIT + RT group presented a significant intervention effect when compared with the control group (Cohen d = 0.23; P < .05). Significant intervention effects were found when comparing the MICT + RT and control groups for body fat percentage, high-density lipoprotein, and VO2peak. Between the HIIT + RT and control groups, significant intervention effects were found for body fat percentage, blood pressure, and VO2peak. There were not significant differences between the HIIT + RT and MICT + RT groups.

CONCLUSION

Twelve weeks of HIIT + RT and MICT + RT were effective in significantly reducing the cardiometabolic risk in these adolescents.

Effects of Creatine Supplementation on Lower-Limb Muscle Endurance Following an Acute Bout of Aerobic Exercise in Young Men

We aimed to determine whether creatine supplementation influences lower-limb muscle endurance following an acute bout of aerobic exercise (AE) in young healthy men. Using a randomized, double-blind, placebo-controlled crossover design, 11 men (26.5 ± 6.2 years, body mass index 26.6 ± 2.1 kg/m²),with 12 months of experience in strength training (three times/week) and AE (two times/week) were randomized to receive creatine (20 g/day plus 20 g/day maltodextrin) and placebo (40 g/day maltodextrin) for 7 days, separated by a washout period of 14 days, before performing an acute bout of AE (30 min on treadmill at 80% baseline maximum velocity) which was followed by four sets of bilateral leg extension endurance exercise using a 10-repetition maximum protocol (10 RM)). There was a significant decrease in the number of repetitions performed in the third (Placebo: −20% vs. Creatine: −22%) and fourth set (Placebo: −22% vs. Creatine: −28%) compared with the first set (p < 0.05), with no differences between creatine and placebo. Additionally, no differences were observed between creatine and placebo for the total number of repetitions performed across all four sets (Placebo: 33.9 ± 7.0 vs. Creatine: 34.0 ± 6.9 repetitions, p = 0.97), nor for total work volume (Placebo: 3030.5 ± 1068.2 vs. Creatine: 3039.8 ± 1087.7 kg, p = 0.98). Short-term creatine supplementation has no effect on lower-limb muscle endurance following an acute bout of aerobic exercise in trained young men.

Effect of Oral Contraceptives on Soft Tissue Injury Risk, Soft Tissue Laxity, and Muscle Strength: A Systematic Review of the Literature

BACKGROUND

Female patients are more likely than male patients to experience various musculoskeletal (MSK) injuries. Because MSK tissues are sensitive to the female hormones relaxin, estrogen, and progesterone, studies have examined whether hormonal contraceptives, which change female hormone levels, can alter the female MSK injury risk. These studies have reached contradictory conclusions, leaving unclear the influence of hormonal contraception on female MSK injury risk.

HYPOTHESIS

Hormonal contraceptives act to decrease female soft tissue injury risk and soft tissue laxity.

STUDY DESIGN

Systematic review; Level of evidence, 3.

METHODS

Reviewers searched for clinically relevant studies evaluating the relationship between hormonal contraceptive use and soft tissue injuries, soft tissue laxity, muscle injuries, and muscle strength in the PubMed, Cochrane, Scopus, CINAHL, and Embase databases. Studies meeting inclusion criteria were scored by 2 independent researchers for risk of bias, imprecision, inconsistency, and indirectness with a template designed using the British Medical Journal Clinical Evidence GRADE (Grades of Recommendation Assessment, Development and Evaluation) scoring system and GRADEPro guidelines. Scores were uploaded into the GRADEPro scoring system software, which calculated each study's final GRADE score (very low, low, moderate, or high quality).

RESULTS

A total of 29 studies met inclusion criteria. Of the 7 studies evaluating oral contraceptive (OC) use and soft tissue injury risk, only 2 received a high quality-of-evidence score; all other studies received a very low score. The high-quality studies concluded that OC use decreases anterior cruciate ligament (ACL) injury risk. Only 1 of the 10 studies evaluating OC use and soft tissue laxity was found to have a high quality of evidence; this study determined that OC use decreases ACL laxity.

CONCLUSION

Higher quality studies suggest that OCs decrease a female patient's risk of ACL injuries and ACL laxity. The strength of these findings, however, is weak. Female patients are up to 8 times more likely to tear their ACLs than male patients. OCs may serve a therapeutic role in decreasing the sex disparity in ACL injury rates.

The compatibility of concurrent high intensity interval training and resistance training for muscular strength and hypertrophy: a systematic review and meta-analysis

The purpose of this systematic review and meta-analysis is to assess the effect of concurrent high intensity interval training (HIIT) and resistance training (RT) on strength and hypertrophy. Five electronic databases were searched using terms related to HIIT, RT, and concurrent training. Effect size (ES), calculated as standardised differences in the means, were used to examine the effect of concurrent HIIT and RT compared to RT alone on muscle strength and hypertrophy. Sub-analyses were performed to assess region-specific strength and hypertrophy, HIIT modality (cycling versus running), and inter-modal rest responses. Compared to RT alone, concurrent HIIT and RT led to similar changes in muscle hypertrophy and upper body strength. Concurrent HIIT and RT resulted in a lower increase in lower body strength compared to RT alone (ES = -0.248, p = 0.049). Sub analyses showed a trend for lower body strength to be negatively affected by cycling HIIT (ES = -0.377, p = 0.074) and not running (ES = -0.176, p = 0.261). Data suggests concurrent HIIT and RT does not negatively impact hypertrophy or upper body strength, and that any possible negative effect on lower body strength may be ameliorated by incorporating running based HIIT and longer inter-modal rest periods.