Interval Training Improves Depressive Symptoms But Not Anxious Symptoms in Healthy Women.

Background: Despite important advances in the relationship between exercise and mood disorders, especially regarding moderate-intensity continuous training, there is a lack of information about the chronic effects of interval training protocols. We compared the effects of two different interval training protocols [sprint interval training (SIT) and high-intensity interval training (HIIT)] on depressive and anxious symptoms in healthy women. Methods: Thirty-six women were randomly allocated to HIIT (n = 18) or SIT (n = 18) groups and performed 24 training sessions over 8 weeks (thrice a week). Levels of state-trait anxiety and depressive symptoms were evaluated using State-Trait Anxiety Inventory and Beck Depression Inventory, respectively, before and after training intervention. Results: Two-way analysis of variance (ANOVA) did not reveal a significant effect of time (p > 0.05), group intervention (p > 0.05), or time × group interaction (p > 0.05) on state-trait anxiety; however, two-way ANOVA showed a significant effect of time on depressive symptoms (p = 0.025) but not group effect (p = 0.548) or time × group interaction (p = 0.373). Depressive symptoms of the participants in both HIIT and SIT groups were reduced from baseline, (ΔHIIT) -17.5 ± 27.9% and (ΔSIT) -28.6 ± 47.5%, respectively. Conclusion: HIIT and SIT groups similarly improved depressive symptoms but not anxiety levels in healthy and physically active young adult women.

Is interval training the magic bullet for fat loss? A systematic review and meta-analysis comparing moderate-intensity continuous training with high-intensity interval training (HIIT).

OBJECTIVES: To compare the effects of interval training and moderate-intensity continuous training (MOD) on body adiposity in humans, and to perform subgroup analyses that consider the type and duration of interval training in different groups. DESIGN: Systematic review and meta-analysis. DATA SOURCES: English-language, Spanish-language and Portuguese-language searches of the electronic databases PubMed and Scopus were conducted from inception to 11 December 2017. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies that met the following criteria were included: (1) original articles, (2) human trials, (3) minimum exercise training duration of 4 weeks, and (4) directly or indirectly compared interval training with MOD as the primary or secondary aim. RESULTS: Of the 786 studies found, 41 and 36 were included in the qualitative analysis and meta-analysis, respectively. Within-group analyses showed significant reductions in total body fat percentage (%) (interval training: -1.50 [95% CI -2.14 to -0.86, p<0.00001] and MOD: -1.44 [95% CI -2.00 to -0.89, p<0.00001]) and in total absolute fat mass (kg) (interval training: -1.58 [95% CI -2.74 to -0.43, p=0.007] and MOD: -1.13 [95% CI -2.18 to -0.08, p=0.04]), with no significant differences between interval training and MOD for total body fat percentage reduction (-0.23 [95% CI -1.43 to 0.97], p=0.705). However, there was a significant difference between the groups in total absolute fat mass (kg) reduction (-2.28 [95% CI -4.00 to -0.56], p=0.0094). Subgroup analyses comparing sprint interval training (SIT) with MOD protocols favour SIT for loss of total absolute fat mass (kg) (-3.22 [95% CI -5.71 to -0.73], p=0.01). Supervised training, walking/running/jogging, age (<30 years), study quality and intervention duration (<12 weeks) favourably influence the decreases in total absolute fat mass (kg) observed from interval training programmes; however, no significant effect was found on total body fat percentage (%). No effect of sex or body mass index was observed on total absolute fat mass (kg) or total body fat percentage (%). CONCLUSION: Interval training and MOD both reduce body fat percentage (%). Interval training provided 28.5% greater reductions in total absolute fat mass (kg) than MOD. TRIAL REGISTRATION NUMBER: CRD42018089427.

Cardiorespiratory and perceptual responses of two interval training and a continuous training protocol in healthy young men.

High Intensity Interval Training (HIIT) can be performed with different effort to rest time-configurations, and this can largely influence training responses. The purpose of the study was to compare the acute physiological responses of two HIIT and one moderate intensity continuous training (MICT) protocol in young men. A randomised cross-over study with 10 men [age, 28.3 ± 5.5years; weight, 77.3 ± 9.3 kg; height, 1.8 ± 0.1 m; peak oxygen consumption (VO2peak), 44 ± 11 mL.kg-1.min-1]. Participants performed a cardiorespiratory test on a treadmill to assess VO2peak, velocity associated with VO2peak (vVO2peak), peak heart rate (HRpeak) and perceived exertion (RPE). Then participants performed three protocols equated by distance: Short HIIT (29 bouts of 30s at vVO2peak, interspersed by 30s of passive recovery, 29 min in total), Long HIIT (3 bouts of 4 min at 90% of vVO2peak, interspersed by 3 min of recovery at 60% of vVO2peak, 21 min in total) and MICT (21 min at 70% of vVO2peak). The protocols were performed in a randomised order with ≥48 h between them. VO2, HRpeak and RPE were compared. VO2peak in Long HIIT was significantly higher than Short HIIT and MICT (43 ± 11 vs 32 ± 8 and 37 ± 8 mL.kg-1.min-1, respectively, P < 0.05), as well as peak HR (181 ± 10 vs 168 ± 8 and 167 ± 11, respectively, P < 0.05), and RPE (17 ± 4 vs 14 ± 4 and 15 ± 4, respectively, P < 0.05), with no difference between Short HIIT and MICT. In conclusion, Long HIIT promoted higher acute increases in VO2, HR and RPE than Short HIIT and MICT, suggesting a higher demand on the cardiorespiratory system. Short HIIT and MICT presented similar physiologic and perceptual responses, despite Short HIIT being performed at higher velocities.

Tabata protocol: a review of its application, variations and outcomes.

PURPOSE: The great popularity of the Tabata Protocol is accompanied by an uncomfortable lack of consistency and criteria in its use, which results in many controversies in the results obtained from its utilization. The purpose of this study was to analyse the studies that based their interventions on the Tabata Protocol and to provide a critical analysis of its use. METHODS: A systematic literature search was conducted in PubMed and Scopus. All articles published between 1996 and October 2017 that cited at least one of the original studies of Tabata et al. were considered. Inclusion criteria were as follows: original articles, human trials and English language. RESULTS: Thirty studies were included for analysis. Almost 37% of the studies (n = 11) used a variation of the Tabata Protocol on a cycle ergometer. Only five studies stated the use of the original Tabata Protocol. Exercise intensity was controlled by percentage of i V ˙ O2 max (n = 8) or i V ˙ O2 peak (n = 3), number of bouts performed (n = 3), all out (n = 10), rate of perceived exertion (n = 1), self-perception of paces (n = 1), maximal power output (n = 1), aerobic power (n = 1) and other forms (n = 2). CONCLUSION: Based on our results, variations of the Tabata Protocol seem to be indicated to provide increases in aerobic power that are similar to traditional aerobic training while being less time consuming. These adaptations seem to be mainly due to peripheral adaptations. Moreover, the use of Tabata Protocols to promote weight loss is not substantiated by the reviewed studies.

Can We Draw General Conclusions from Interval Training Studies?

Interval training (IT) has been used for many decades with the purpose of increasing performance and promoting health benefits while demanding a relatively small amount of time. IT can be defined as intermittent periods of intense exercise separated by periods of recovery and has been divided into high-intensity interval training (HIIT), sprint interval training (SIT), and repeated sprint training (RST). IT use has resulted in the publication of many studies and many of them with conflicting results and positions. The aim of this article was to move forward and understand the studies' protocols in order to draw accurate conclusions, as well as to avoid previous mistakes and effectively reproduce previous protocols. When analyzing the literature, we found many inconsistencies, such as the controversial concept of 'supramaximal' effort, a misunderstanding with regard to the term 'high intensity,' and the use of different strategies to control intensity. The adequate definition and interpretation of training intensity seems to be vital, since the results of IT are largely dependent on it. These observations are only a few examples of the complexity involved in IT prescription, and are discussed to illustrate some problems with the current literature regarding IT. Therefore, it is our opinion that it is not possible to draw general conclusions about IT without considering all variables used in IT prescription, such as exercise modality, intensity, effort and rest times, and participants' characteristics. In order to help guide researchers and health professionals in their practices it is important that experimental studies report their methods in as much detail as possible and future reviews and meta-analyses should critically discuss the articles included in the light of their methods to avoid inappropriate generalizations.