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Reducing training frequency from 3 or 4 sessions/week to 2 sessions/week does not attenuate improvements in maximal aerobic capacity with reduced-exertion high-intensity interval training (REHIT)

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Abstract

In the present randomised-controlled trial we investigated the effect of reduced-exertion high-intensity interval training (REHIT) training frequency (2, 3, or 4 sessions/week for 6 weeks) on maximal aerobic capacity in 42 inactive individuals (13 women; mean ± SD age: 25 ± 5 years, maximal aerobic capacity: 35 ± 5 mL·kg ⁻¹ ·min ⁻¹ ). Changes in maximal aerobic capacity were not significantly different between the 3 groups (2 sessions/week: +10.2%; 3 sessions/week: +8.1%; 4 sessions per week: +7.3%). In conclusion, a training frequency of 2 sessions/week is sufficient for REHIT to improve maximal aerobic capacity. Novelty We demonstrate that reducing REHIT training frequency from 3 or 4 to 2 sessions/week does not attenuate improvements in the key health marker of maximal aerobic capacity.
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      AB    C     
 $  ,  4   A ,   
  $   4 8"R ?62:? "   
   C     D   ; 
     "+04 $ 69 O9
 P C  (FG, 69 
8& ?6<:? A$   
4C   9   
  A $      ? 4   9
;    $$;   ; 
4N $(FG,;  AB $
$  8( ?65:?
 $   A$   B 
    $  , 4     
 $D?  A $       C  $
   8"H O9 P $S6: 8 ?
6%: 9     8044H  8A9:, 
$T/6:8  ?6<:  B  
(FG, ;  R   E; $ < ; A    A $ 
;  C $  $D     (FG,  
 4    A  ?  "+04  
 4  $D$E;8(
?65:?4 A  ; $D; $
  , ?  $D
 A ,           A
 ? $   ;   C $
$D8%E;: (FG,
/ ; $ "+04    ? .     
 $D ;     $    ;  
   ;  $D$%E;?
%
0'$!#'1*',.0!$"-.*
2
         ;   %     -1
8=E3  ; . :    
$ "+04 AA# $ ?86:
A   8"+04:  8"+04:  % 8"+04%:   
;? "  ; $        ?
+, ;B    
4    7 847:   ,
      D 8"9
7:  B   8U%6E26  0:      
T66 A L9?  9         A 5
   $  8"+04JV8J$ $:H
"+04%JV%8 $ ::?  
$           ;   *$  *3
8. J V<  J V2 ;J V2 - J V/:?   ;
        E       $ 
 $  ? - + 8&4"85E<9
/:H 6/9:?     ;  $  $;  
A, $   ?
!2
     ,  ;    (FG,
8+,A   3   & H (J Q%M:?   
 ;   ,   8G,  'H '
(  ( #   H   ,  # !   ,H  7 9+
K
:?   ;D  $  ,E
C      $
;  A$  ?     ; K9;98K6
.: $  ;     ;  A .    
, ?(FG, ;   $K9A 
    $ T $  $;   ;  J :  
, :"+"U?K:,  ; 6A $ 9
 ,8??69:?; $  ?
  AD $ , ;$"+04 $ %
,;?"+046$
   ;    9           $ 5?KM  $  
  PA8+<5%#;:?  ;
6;K;6 %;?B 
B   B 5?D  
 A $     8A ?6/: ;   $ 
 ,?   9  (FG,  ; 
$;  ?=  "+      C 
 "+04 ; A    
A 8 ?62:?
*
=  I=?  C (FG,
A ;  ; C !$fV6?K;$<6MWV6?6K
     ; D  ? ;9; , 
&G(  8  8"+04E"+04E"+04%:: X   8E ::  ;    
 C A ; $Y(FG, $YA?
19. 0  ;    C A ;  
$   A ?B;  S6?6K?
/
!*/1$*
G 8M$A  : ;
B  C A ;    822M $ "+04 2<M $
"+04 22M $ "+04%:? & B $9 9  
;  A  $ A    8"+04J <%?KI6?5 ?  <%?KI6?/  H  "+04J
56?/IK?2? 5?I/?6 H "+04%J 52?I5?< ? 5<?<I5?:?  ; 
B   A  (FG, 8><?5MH  C $ J
S6?66: A  B )     C    
     8"+04J >6?M "+04J ><?M "+04 %J
>5?MH43:?
 A  $  "+04    ;  8* $
*:?G  P      "+04;
RA   ;P  9A       
 ;  "+04    $ ;   $   ;  
 "+04  ; "+04   ?  
 ;    "+04;   , ? 
;B CA ; $$ ?
5
.#*&/**#-,
   R $ 4  $D
$E;A   A $; $
R B ;  ; A   O P  $D8??    
;    (FG, 
  ;        (FG,:?  
       C $  $D 8  %
E;:        (FG,   / ; $ "+04 
 ? B  ;    $ "+04
;$/;N  B (FG,
 $  % E;   B   
 $  ? A$  ; 4
8( ?65:   $ ,;
  A$  (FG,$4?B
  A $    A ,
81 ?66/H1 ?662H  ?66:  
A$ ;$ C    
D   ?
  $ B      (FG, ;   % "+04
E;  E;      ?
  ,    8
?665:A    ;$"+048E;:N
   A;"+04 (FG,
,  ; 8%E;:? $
B$  A ? 862:; 
  (FG,;  ;9;04486,/6 Q<M
<
$;: B C $ ;   
$  E;?
4  ; ;     $D 8U% E;:
   $  (FG,  ;  ;
 $D 8 E;: ; A N ?  ;  A
 A$  ?
  A $         A  ?
  ; AB dierence  $
   (FG, A ; "+04   $     %
E;  ; ;   $   equivalence $ 
 ?;   $ ;;
,  $C $$,,A(FG,
; , A $ C    $ C 
    9  ?  ;     C $
 $D    (FG,   ; ; 
 $D C    $       
A  A ?
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#$"#&#3'G
.$ ;  ?
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      $      ?
Biology (Basel), 38:J9%%?J6?26EA66
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 , A 
 ?Tech. Coloproctol. 208/:J5K9<?J6?665E6K96/9
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 1??0??0?'?;?&?*A
#? '? 66K? ,  $      
,           ? J. Appl.
Physiol. (1985), 988/:J2<K9226?J6?KER?662K?66%
??+ ??'??*?&?665?+C $C
 $       B   
;    A     ;  ;      A
J   !     ? JAMA, 29782:J  6<962?
J6?66ER?25?2?6<
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4? #? ? 6?   $   #    ?
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# $"??AR'??;??*(&??6?; 
  $ , $   A  J AB
C  $ 9,  9     ? Eur. J. Appl.
Physiol. 11285:J5/5955K?J6?665E66%969K%9!
& ? "?  ?  !  ? 3? [!A [?  &? +?
# $ "? ? ?6<? =  $ 6 6
9, 9    8"+04:  
  , A  A  C  C 
   ? Appl. Physiol. Nutr. Metab. 438%:J  <9%%?
J6?2E96596K25
"R  =?  3  =?  .$  ?  \$  [?  0  0? '?  *    '?  62?
 $ $9    
   J  9? Scand. J. Med. Sci. Sports
J6?E?%K
"N'???0 #?+=?"A?#?
=? ?65?  $    AB $ 9, 
9    8"+04: 9  ;

 A    ? Appl. Physiol. Nutr. Metab. 428:J  696<?
J6?2E96/96%25
?&? ! ?3? ! ?#= ?#
? ? 62? C       9
,  9       8"+04:? Int. J. Sport Exer. Psych?
J?E6?6<6E/25]?62?K25
 ?????=?!?*0RA
#?  6<?  09    4     DJ  A
+C     7   $  3$? Int. J. Sports Med. 398:J  695?
J6?6KKE966%9K65%
 ?????=?!?*0RA
#?62?+C $9    $D 
  $        ? Appl. Physiol. Nutr.
Metab. 4482:J2K92K5?J6?2E96<96565
 ??G;&??+?'??*;.?66? $
 ^        J ;   ? Med. Sci.
Sports Exerc. 348:J  22/966?
J6?%2E6?#?66666<25%?5/266?2
( &?? '? *# $ "? ?65? "   0  B  $
 4  ; ; 
 ?Sports Med. 478:J%%9%K?J6?665E%65296596559,
(&??'?# $"??*.?65?+C $&A$ 
4(G,J# 9?Med. Sci. Sports
Exerc. 498/:J%59K/?J6?%2E#?6666666666666%

4 3   (FG, /;$"+04$
 $D $   %   ;?  ;  B
CA ; $  9(FG,?
%
*$*3    
!"#$

 637%
!"#$

 63%
!"#$


63%
* % E% <E/ 2E
' % /I/ /IK %I%
)0# 8%5?I%?/ %?I%? /?2I?%
)9
:- 18383%%?%I/? K?5I%?< /?I%?<
2 0!$
83%%KI/2 K/KI/ K%I65
Values shown are means±SD. Physical activity level was estimated using the IPAQ.
K
*$* A $"+04
!"#$

 637%
!"#$

 63%
!"#$


63%
#;!"#$ ?/I6?K ?/I6?< ?2I6?5
!"#$ ?2I? ?2I? ?/I?
#!"#$
 ?KI6?/ ?%I6?K ?2I6?K
!"#$
 ?/I? ?%I6?< ?2I?
#!"#$ ?/I6?K ?%I6?/ ?I6?2
$
!"#$ %?6I? ?2I? ?/I?%
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Values shown are means±SD. Responses are given on a 5-point Likert scale ranging from
1 (strongly agree) to 5 (strongly disagree).
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... displeasure) varies between different SIE protocols, and is particularly dependent on the interaction between the number and duration of sprint efforts. Our data indicate that positive valence can be maintained during SIE by using up to 2 repetitions of longer sprint durations [15-30 s; termed "reduced-exertion high-intensity interval training" (REHIT) (Metcalfe et al., 2012(Metcalfe et al., , 2015(Metcalfe et al., , 2016Ruffino et al., 2017;Nalçakan et al., 2018;Thomas et al., 2020)] or by using multiple sprints of shorter duration [5-6 s; (Niven et al., 2018;Bradley et al., 2019)]. Each of these SIE protocol variants has evidence for their efficacy at improving key health markers (Metcalfe et al., 2012(Metcalfe et al., , 2016Adamson et al., 2014Adamson et al., , 2019Adamson et al., , 2020Ruffino et al., 2017;Nalçakan et al., 2018;Thomas et al., 2020), whilst recent pilot work has shown that REHIT may be feasible and effective in a 'real-world' workplace setting in the short term (Metcalfe et al., 2020). ...
... Our data indicate that positive valence can be maintained during SIE by using up to 2 repetitions of longer sprint durations [15-30 s; termed "reduced-exertion high-intensity interval training" (REHIT) (Metcalfe et al., 2012(Metcalfe et al., , 2015(Metcalfe et al., , 2016Ruffino et al., 2017;Nalçakan et al., 2018;Thomas et al., 2020)] or by using multiple sprints of shorter duration [5-6 s; (Niven et al., 2018;Bradley et al., 2019)]. Each of these SIE protocol variants has evidence for their efficacy at improving key health markers (Metcalfe et al., 2012(Metcalfe et al., , 2016Adamson et al., 2014Adamson et al., , 2019Adamson et al., , 2020Ruffino et al., 2017;Nalçakan et al., 2018;Thomas et al., 2020), whilst recent pilot work has shown that REHIT may be feasible and effective in a 'real-world' workplace setting in the short term (Metcalfe et al., 2020). There remains a need for future research to assess the longer-term effectiveness of SIE (and HIIE) for improving health. ...
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Responses to sprint interval exercise (SIE) are hypothesized to be perceived as unpleasant, but SIE protocols are diverse, and moderating effects of various SIE protocol parameters on affective responses are unknown. We performed a systematic search to identify studies (up to 01/05/2021) measuring affective valence using the Feeling Scale during acute SIE in healthy adults. Thirteen studies involving 18 unique trials and 316 unique participant (142 women and 174 men) affective responses to SIE were eligible for inclusion. We received individual participant data for all participants from all studies. All available end-of-sprint affect scores from each trial were combined in a linear mixed model with sprint duration, mode, intensity, recovery duration, familiarization and baseline affect included as covariates. Affective valence decreased significantly and proportionally with each additional sprint repetition, but this effect was modified by sprint duration: affect decreased more during 30 s (0.84 units/sprint; 95% CI: 0.74–0.93) and 15–20 s sprints (1.02 units/sprint; 95% CI: 0.93–1.10) compared with 5–6 s sprints (0.20 units/sprint; 95% CI: 0.18–0.22) (both p < 0.0001). Although the difference between 15–20 s and 30 s sprints was also significant ( p = 0.02), the effect size was trivial ( d = −0.12). We observed significant but trivial effects of mode, sprint intensity and pre-trial familiarization, whilst there was no significant effect of recovery duration. We conclude that affective valence declines during SIE, but the magnitude of the decrease for an overall SIE session strongly depends on the number and duration of sprints. This information can be applied by researchers to design SIE protocols that are less likely to be perceived as unpleasant in studies of real-world effectiveness. Systematic Review Registration Open Science Framework, https://osf.io/sbyn3 .
... Previously, REHIT has been identified as a more effective modality to improve CRF (Metcalfe et al., 2012;Ruffino et al., 2017), with the improvements in FFI presented in this study further supporting this, as CRF is a component of the FFI. The exact mechanism behind why REHIT is more effective than MICT at improving CRF is still under investigation, given that more volume is usually expected to produce greater improvements in CRF (Thomas et al., 2020). Metcalfe et al. (2015) found significant reductions in muscle glycogen and increased gene expression despite the short duration of REHIT sessions. ...
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Background Many adults do not reach the recommended exercise participation guidelines, often citing lack of time as a barrier. Reduced exertion high-intensity training (REHIT) is a mode of exercise that takes as few as 10 min and has been shown to be as effective as other modalities. The Fitness Fatness Index (FFI) is a recently developed index that is used to predict cardiovascular disease (CVD) risk. The aim of this study was to determine the efficacy of a REHIT vs. a traditional moderate-intensity continuous training (MICT) on FFI in physically inactive adults. Methods Thirty-two participants were randomized into one of two 8-week exercise intervention groups: (i) REHIT ( n = 16); (ii) MICT ( n = 16). The REHIT group performed 10 min of individualized cycling intervals on 2–4 days of the week. The MICT group were prescribed aerobic exercise at 50–65% of their heart rate reserve (HRR) on 3–5 days of the week. FFI was recorded at baseline and post 8-weeks, with FFI being calculated as cardiorespiratory fitness (CRF) (expressed as metabolic equivalents) divided by waist to height ratio (WtHR). A 1-unit increase in FFI was recognized as a clinically significant change in FFI. Results The REHIT group showed significantly greater (+1.95, ±0.63) improvements in FFI compared to those in the MICT (+0.99, ±0.47) group (between group difference, p < 0.001). Furthermore, there was a greater proportion of participants who achieved a clinically significant change in FFI in the REHIT group (12/12, 100%) than in the MICT group (8/15, 53%) (between group difference, p = 0.01). Conclusion This study suggests that REHIT may be a more efficacious exercise modality to increase FFI than MICT. This outcome is beneficial as the clinician can prescribe REHIT to physically inactive adults who cite lack of time as a barrier to physical activity participation and achieve significant reductions in CVD risk.
... Thus, the two general physical fitness indicators of baseball players, namely, 50 m and standing long jump, were determined. The third round of questionnaire opinions was not collected [24]. ...
Article
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Baseball itself is a new sport. In the process of training, teachers often use traditional training methods, which leads to unsatisfactory training results. High-intensity intermittent and intensive interval training can better improve the efficiency of athletes’ oxidation and energy supply and ultimately play a positive role in improving athletes’ performance. This paper takes the influence of high-intensity and intensive interval training on the special endurance of baseball players as the research object. A series of functional training programs are developed through adaptive training, testing, coordination training, and recovery training. Through the use of experimental means to understand the influence of high-intensity interval training and intensive interval training on the physical fitness of baseball players, the paper is aimed at providing ways and means to improve the physical fitness level of baseball players in the future. Based on the experimental test data, functional training is different from traditional training methods to make up for the lack of training research. It is to improve the competitive ability of our baseball players and promote the development of our baseball. It plays an active role in improving the specific endurance, speed, and intermittent endurance of baseball players.
... Ces modalités utilisent bien l'alternance entre des efforts de haute intensité et des périodes de récupération mais ne s'effectuent pas à l'intensité spécifique du HIIT (80 -100% de VO2max). Ces différentes modalités montrent tout de même une efficacité sur les capacités aérobies mais aussi la sensibilité à l'insuline et la composition 53 corporelle (Gibala et al., 2012;Gibala & Little, 2020;Gillen et al., 2016;Metcalfe et al., 2012;Reljic et al., 2020;Sabag et al., 2021;Thomas et al., 2020;Vollaard & Metcalfe, 2017;Zhang et al., 2021). Cependant, la perte de poids et de MG comparativement au HIIT seraient limitées avec ces modalités d'entrainement (Sultana et al., 2019). ...
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La prévention primaire et secondaire des pathologies inflammatoires chroniques telles que l’obésité et la maladie de Crohn (MC) reposent majoritairement sur des mesures hygiéno-diététiques incluant l’activité physique et la nutrition. Dans le cadre de ce travail de thèse, l’objectif principal était d’étudier l’influence de modalités d’exercice - exercice imposé de type intermittent de haute intensité (HIIT) ou activité de roue spontanée - associé à un apport en lin, riche en acides gras polyinsaturés (AGPI) n-3, sur les interrelations « composition corporelle – inflammation – microbiote intestinal » dans un contexte de pathologies inflammatoires chroniques (obésité, MC) sur modèles murins. Le deuxième objectif était d’étudier spécifiquement deux formes de lin, à travers la graine ou l’huile, afin de déterminer si la matrice de la graine de lin extrudée pouvait avoir des effets qui lui sont propres. Nos résultats indiquent qu’un programme de type HIIT est efficace pour prévenir la prise de poids et de masse grasse, et que le lin, indépendamment de sa forme, diminue l’inflammation. Nos travaux ont également montré un effet majeur du HIIT et de la graine de lin extrudée (TRADILIN, Valorex®) sur la modulation de la composition du microbiote intestinal associé à la muqueuse. Certaines de ces variations étaient corrélées aux modulations de la composition corporelle mais non à l’inflammation. Nos travaux ont montré spécifiquement un effet synergique du HIIT et de l’huile de lin sur l’abondance d’Oscillospira spp. et sur la conversion de l’acide α-linolénique en acide docosahexaénoïque. En conclusion, nos résultats montrent qu’un apport en lin, et particulièrement sous forme de graines extrudées, associé à une activité physique imposée et suffisamment intense, pourraient être efficace dans la prévention et/ou la prise en charge des pathologies inflammatoires chroniques telles que l’obésité et la MC. Les interrelations « composition corporelle – inflammation – microbiote intestinal », restent toutefois à approfondir et les mécanismes sous-jacents à explorer.
... Hence, it has been proposed that future studies should focus on the investigation of protocols with fewer sprint repetitions and lesser sprint time duration [8,9]. Accordingly, less demanding SIT protocols have been developed (e.g., 2x 20-second sprints in a 10-minute training session) and their effects on various health-related parameters (excluding cognitive performance such as changes in attentional performance) have been investigated [10][11][12][13]. ...
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Considerable evidence has been accumulated showing that an acute bout of physical exercise can improve cognitive performance but the optimal exercise characteristics (e.g., exercise type and intensity) remain elusive. In this regard, there is a gap in the literature to which extent Sprint Interval Training (SIT) can enhance cognitive performance. Thus, this study aimed to investigate the effect of SIT on cognitive performance. We assessed in healthy younger adults (n = 19; 20.0 to 28.0 years old), the attentional performance (via d2 test), the working memory performance (via Digit Span Forward/ Backward) and the peripheral blood lactate concentration immediately before and 10 minutes after an exercise condition (SIT) and a control condition (i.e., reading). We observed that SIT can enhance specific aspects of attentional performance as it improved F% (t (19) = -2.249, p = 0.037, d = − 0.516) which constitutes a qualitative measure of precision and thoroughness. However, SIT did not change other measures of attentional or working memory performance. In addition, we observed that the exercise-induced increase in peripheral blood lactate levels correlated with changes in attentional performance (e.g., F% (rm = -0.54, p = 0.015)). The present study provides initial evidence that a time-efficient SIT can improve specific aspects of attentional performance and conforming evidence for a positive link between cognitive improvements and changes in peripheral blood lactate levels. Further research is warranted to substantiate our findings by investigating (i) the optimal exercise characteristics (e.g., number of sprints), (ii) further neurobiological mechanisms driving the cognitive improvements (e.g., changes in functional brain activation patterns), and (iii) the generalizability of the effects (e.g., older adults).
... In fact, IT protocols that induced these metabolic responses have been associated with negative immune outcomes and increased risk of illness [84,85,[92][93][94]. Therefore, some strategies might be used to alleviate this responses, like to reduce the duration of the sprints to less than 15 s [95][96][97], reduce the number of sprints [95,98], increase rest duration and perform active rest between sprints [99] or reduce weekly training frequency [100]. Moreover, caution should be taken with training schedule and weekly volume since consecutive days of two daily IT sessions induce acute immunosuppression and increased risk for infection [101,102]. ...
Article
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Aerobic exercise is traditionally recommended to improve general health and prevent many non-communicable diseases. However, the measures adopted to control the novel Coronavirus (COVID-19) outbreak culminated with closing of exercise facilities and fitness centers and, as a primary consequence, impaired aerobic exercise practice. This contributed to an increase in risk factors associated with physical inactivity such as insulin resistance, high blood pressure, low-grade inflammation, weight gain, and mental health problems. The scenario is worrisome, and it is important to propose alternatives for exercise practice during the COVID-19 pandemic. Interval training (IT) emerges as an exercise mode that might be feasible, low-cost, and potentially safe to be performed in many different places. IT consists of interspersing relative brief bouts of high-intensity exercise with recovery periods and promotes similar or greater health benefits when compared to moderate-intensity continuous exercise. Among the different types of IT, sprint interval training and "Tabata protocols" might be particularly useful during social isolation. These protocols can be controlled and performed without the need of complex equipment and can be adapted to different places, including domestic environments. In this article, we present variations of IT as possible alternatives to cope physical inactivity during COVID-19 pandemics with a focus on its practical applications. The protocols suggested can be performed without the need of specialized equipment or facilities, in a time-efficient manner, and aiming to prevent detraining or even improve physical fitness and general health.
Thesis
La prise en charge de l’obésité et/ou du pré-diabète, deux états pathologiques favorisant le développement d’un diabète de type 2 (DT2) et l’apparition de maladies cardiovasculaires, repose majoritairement sur des mesures hygiéno-diététiques incluant l’activité physique et l’alimentation. Dans ce cadre, les objectifs principaux de cette thèse étaient d’étudier les effets de plusieurs modalités d’entrainement -dont l’entrainement intermittent de haute-intensité (HIIT)-, associées ou non avec Totum-63 (T63, Valbiotis®), un mélange à base d’extraits végétaux, sur la perte de masse grasse totale et (intra-)abdominale et sur l’équilibre glycémique. Différentes pistes mécanistiques explicitant ces effets ont également été investiguées et en particulier le rôle du microbiote intestinal. Nos résultats indiquent qu’un programme de HIIT combiné ou non à du renforcement musculaire est une stratégie efficace et sans danger pour favoriser une perte de masse grasse totale et (intra-)abdominale. Par ailleurs, la prise concomitante de T63 lors d’un entrainement HIIT s’est révélée positive pour améliorer l’équilibre glycémique. Nos travaux ont également montré une modulation spécifique du microbiote intestinal en réponse à chacune de ces interventions. En conclusion, nos résultats indiquent que ces prises en charge novatrices pourraient être proposées à des patients à risque pour éviter l’apparition du DT2 ou autres conséquences métaboliques liées au surpoids ou à l’obésité. L’influence directe du microbiote dans ces adaptations restent toutefois à démontrer.
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Interindividual variability for training-induced changes in maximal oxygen uptake (V̇O 2max ) is well described following continuous aerobic and high-intensity interval training. Whether similar variability is observed following time-efficient sprint interval training with minimal training volume (i.e., reduced-exertion high-intensity interval training; REHIT) is unknown. We conducted a pooled analysis of n = 117 (68 men) training participants (mean ± SD: age: 30 ± 10 y; V̇O 2max : 34.8 ± 7.5 mL·kg ⁻¹ ·min ⁻¹ ), who completed a V̇O 2max assessment before and 3 days after 6 weeks of REHIT comprising of two 10–20-s ‘all-out’ cycling sprints per session, and n = 40 no-intervention control participants (age: 30 ± 13 y; V̇O 2max : 31.5 ± 6.5 mL·kg ⁻¹ ·min ⁻¹ ) who completed repeated V̇O 2max tests over a comparable timeframe. Individual responses estimated using 50% confidence intervals derived from the technical error were interpreted against a smallest worthwhile change of 1.75 mL·kg ⁻¹ ·min ⁻¹ . The standard deviation of individual responses was 2.39 mL·kg ⁻¹ ·min ⁻¹ demonstrating clinically meaningful heterogeneity in training-induced changes in V̇O 2max following REHIT that exceed the technical, biological and random within-subjects variability of V̇O 2max assessment. The likely (75% probability) non-response rate was 18% (21/117), and 49% (57/117) of individuals demonstrated increases in V̇O 2max likely higher than the smallest worthwhile change. We conclude that the well-described increase in V̇O 2max following REHIT at the group level is subject to substantial variability in magnitude at an individual level. This has important implications for exercise prescription and can be harnessed to elucidate mechanisms of adaptation. Novelty: There is substantial heterogeneity in V̇O 2max responses following time-efficient sprint interval training. Proportion of non-response was 18% and ∽50% of individuals show clinically meaningful increases in V̇O 2max .
Article
The aims of this study were to investigate the influence of reduced-exertion, high-intensity interval training (REHIT), comparing a novel shortened-sprint protocol (SSREHIT) against a traditional protocol (TREHIT), on perceptual responses and to determine if changes in peak oxygen uptake (V˙O2peak) are attenuated with shorter sprints. Twenty-four healthy men undertook 15 sessions of SSREHIT or TREHIT. V˙O2peak was determined at baseline and after completion of each exercise condition. Affective (pleasure-displeasure) responses and perceived exertion were assessed during exercise to capture peak responses. Enjoyment was recorded 5-min after cessation of exercise. Compared to baseline, V˙O2peak increased in both groups (6% for SSREHIT [d=- 0.36] and 9% for TREHIT [d=- 0.53], p=0.01). Affective responses were more favourable for SSREHIT (p=0.001, d=1.62), but both protocols avoided large negative peaks of displeasure. Peak ratings of perceived exertion were lower for SSREHIT (p=0.001, d=- 1.71), although there were no differences in enjoyment (d=0.25). The results demonstrate both exercise conditions can increase V˙O2peak without overly compromising perceptual responses. Decreased sprint duration might further circumvent negative perceptual responses but might also attenuate physiological adaptations.
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Recent evidence suggests that high‐intensity interval training (HIIT) is an effective method to improve fitness and various health‐markers. However, the tolerability and acceptability of HIIT among sedentary individuals is currently controversially discussed. Therefore, our objective was to investigate the prevalence and predictors of dropout among sedentary individuals in HIIT‐based exercise interventions. MEDLINE/PubMed, SPORTDiscus and Web of Science were searched systematically for relevant articles until 06/2018. Studies included were required to (1) be written in English, (2) include sedentary healthy adults, (3) use some form of HIIT without any complementary intervention, (4) last ≥4 weeks, (5) report detailed description of the applied HIIT‐protocol, (6) report data that allows calculation of a dropout rate. Fifty‐five studies reporting results from 67 HIIT‐interventions with 1318 participants met the eligibility criteria. The trim and fill adjusted pooled dropout rate across all interventions was 17.6% (95% confidence interval 14.2–21.5%). Dropout rates were significantly lower in cycling‐based interventions compared with studies using running/walking as exercise‐modality (P<.001). Longer session time (β=0.02, P<.05), higher time effort/week (β=0.005, P<.05) and overall time effort/intervention (β=0.0003, P<.05) predicted greater dropout. Exercise intensity was not related to dropout. Our data suggest that HIIT‐based interventions are tolerable and acceptable for previously sedentary individuals, exhibiting generally lower dropout rates than commonly reported for traditional exercise‐programs. Given the association between HIIT‐volume and dropouts, future studies should further focus on identifying the minimally effective dose of practical HIIT for improving health status. Such efforts would be important to increase implementation and public health impact of HIIT. This article is protected by copyright. All rights reserved.
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We have previously demonstrated that reduced-exertion high-intensity interval training (REHIT) is a genuinely time-efficient exercise strategy for improving cardiometabolic health. Here, we examined the affective and perceptual responses to REHIT. Eight young men and women (age 21 ± 1 y, BMI 24.9 ± 2.1 m/kg2, V̇O2max 39 ± 10 ml/kg/min) and 11 men with type 2 diabetes (T2D; age 52 ± 6 y, BMI 29.7 ± 3.1 m/kg2, V̇O2max 29 ± 5 ml/kg/min) took part in three-arm crossover trials with RPE and affective valence measured during, and enjoyment and exercise preferences measured following either: 1) REHIT (2 × 20-s sprints in a 10-min exercise session), 2) HIIT (10 × 1-min efforts) and 3) 30 min MICT. Furthermore, 19 young men and women (age 25 ± 6 y, BMI 24 ± 4 m/kg2, V̇O2max 34 ± 8 ml/kg/min) completed a 6-week REHIT intervention with affective valence during an acute REHIT session measured before and after training. Affect decreases (briefly) during REHIT, but recovers rapidly, and the decline is not significantly different when compared to MICT or HIIT in either healthy participants or T2D patients. Young sedentary participants reported similar levels of enjoyment for REHIT, MICT and HIIT, but 7 out of 8 had a preference for REHIT. Conversely, T2D patients tended to report lower levels of enjoyment with REHIT compared with MICT. The decrease in affective valence observed during an acute REHIT session was significantly attenuated following training. We conclude that affective and perceptual responses to REHIT are no more negative compared to those associated with MICT or HIIT, refuting claims that supramaximal sprint interval training protocols are associated with inherent negative responses.
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Purpose: Recent studies have demonstrated that modifying the 'classic' 6x30-s 'all-out' sprint interval training (SIT) protocol by incorporating either shorter sprints (6x10-s or 15-s sprints) or fewer sprints (e.g. 2x20-s sprints; reduced-exertion high-intensity interval training (REHIT)) does not attenuate the training-induced improvements in maximal aerobic capacity (V̇O2max). The aim of the present study was to determine whether reducing the sprint duration in the REHIT protocol from 20 s to 10 s per sprint influences acute affective responses and the change in V̇O2max following training. Methods: Thirty-six sedentary or recreationally active participants (17 women; mean±SD age: 22±3 y, BMI: 24.5±4.6 kg·m-2, V̇O2max: 37±8 mL·kg-1·min-1) were randomised to a group performing a 'standard' REHIT protocol involving 2x20-s sprints or a group who performed 2x10-s sprints. V̇O2max was determined before and after 6 weeks of 3 weekly training sessions. Acute affective responses and perceived exertion were assessed during training. Results: Greater increases in V̇O2max were observed for the group performing 20-s sprints (2.77±0.75 to 3.04±0.75 L·min-1; +10%) compared to the group performing 10-s sprints (2.58±0.57 vs. 2.67±3.04 L·min-1; +4%; group×time interaction effect: p<0.05; d=1.06). Positive affect and the mood state vigour increased post-exercise, while tension, depression and total mood disturbance decreased, and negative affect remained unchanged. Affective responses and perceived exertion were not altered by training and were not different between groups. Conclusion: Reducing sprint duration in the REHIT protocol from 20 s to 10 s attenuates improvements in V̇O2max, and does not result in more positive affective responses or lower perceived exertion.
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Over the past decade, it has been convincingly shown that regularly performing repeated brief supramaximal cycle sprints (sprint interval training [SIT]) is associated with aerobic adaptations and health benefits similar to or greater than with moderate-intensity continuous training (MICT). SIT is often promoted as a time-efficient exercise strategy, but the most commonly studied SIT protocol (4-6 repeated 30-s Wingate sprints with 4 min recovery, here referred to as 'classic' SIT) takes up to approximately 30 min per session. Combined with high associated perceived exertion, this makes classic SIT unsuitable as an alternative/adjunct to current exercise recommendations involving MICT. However, there are no indications that the design of the classic SIT protocol has been based on considerations regarding the lowest number or shortest duration of sprints to optimise time efficiency while retaining the associated health benefits. In recent years, studies have shown that novel SIT protocols with both fewer and shorter sprints are efficacious at improving important risk factors of noncommunicable diseases in sedentary individuals, and provide health benefits that are no worse than those associated with classic SIT. These shorter/easier protocols have the potential to remove many of the common barriers to exercise in the general population. Thus, based on the evidence summarised in this current opinion paper, we propose that there is a need for a fundamental change in focus in SIT research in order to move away from further characterising the classic SIT protocol and towards establishing acceptable and effective protocols that involve minimal sprint durations and repetitions.
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Reduced-exertion high-intensity interval training (REHIT) is a genuinely time-efficient intervention that can improve aerobic capacity and insulin sensitivity in sedentary individuals. The present study compared the effects of REHIT and moderate-intensity walking on health markers in patients with type 2 diabetes (T2D) in a counter-balanced crossover study. Sixteen men with T2D (mean ± SD age: 55 ± 5 years, body mass index: 30.6 ± 2.8 kg·m(-2), maximal aerobic capacity: 27 ± 4 mL·kg(-1)·min(-1)) completed 8 weeks of REHIT (three 10-min low-intensity cycling sessions/week with two "all-out" 10-20-s sprints) and 8 weeks of moderate-intensity walking (five 30-min sessions/week at an intensity corresponding to 40%-55% of heart-rate reserve), with a 2-month wash-out period between interventions. Before and after each intervention, participants underwent an incremental fitness test, an oral glucose tolerance test (OGTT), a whole-body dual-energy X-ray absorptiometry scan, and continuous glucose monitoring. REHIT was associated with a significantly larger increase in maximal aerobic capacity compared with walking (7% vs. 1%; time × intervention interaction effect: p < 0.05). Both REHIT and walking decreased resting mean arterial pressure (-4%; main effect of time: p < 0.05) and plasma fructosamine (-5%; main effect of time: p < 0.05). Neither intervention significantly improved OGTT-derived measures of insulin sensitivity, glycaemic control measured using continuous glucose monitors, blood lipid profile, or body composition. We conclude that REHIT is superior to a 5-fold larger volume of moderate-intensity walking in improving aerobic fitness, but similar to walking REHIT is not an effective intervention for improving insulin sensitivity or glycaemic control in T2D patients in the short term.
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Aims: We investigated whether sprint interval training (SIT) was a time-efficient exercise strategy to improve insulin sensitivity and other indices of cardiometabolic health to the same extent as traditional moderate-intensity continuous training (MICT). SIT involved 1 minute of intense exercise within a 10-minute time commitment, whereas MICT involved 50 minutes of continuous exercise per session. Methods: Sedentary men (27±8y; BMI = 26±6kg/m2) performed three weekly sessions of SIT (n = 9) or MICT (n = 10) for 12 weeks or served as non-training controls (n = 6). SIT involved 3x20-second 'all-out' cycle sprints (~500W) interspersed with 2 minutes of cycling at 50W, whereas MICT involved 45 minutes of continuous cycling at ~70% maximal heart rate (~110W). Both protocols involved a 2-minute warm-up and 3-minute cool-down at 50W. Results: Peak oxygen uptake increased after training by 19% in both groups (SIT: 32±7 to 38±8; MICT: 34±6 to 40±8ml/kg/min; p<0.001 for both). Insulin sensitivity index (CSI), determined by intravenous glucose tolerance tests performed before and 72 hours after training, increased similarly after SIT (4.9±2.5 to 7.5±4.7, p = 0.002) and MICT (5.0±3.3 to 6.7±5.0 x 10-4 min-1 [μU/mL]-1, p = 0.013) (p<0.05). Skeletal muscle mitochondrial content also increased similarly after SIT and MICT, as primarily reflected by the maximal activity of citrate synthase (CS; P<0.001). The corresponding changes in the control group were small for VO2peak (p = 0.99), CSI (p = 0.63) and CS (p = 0.97). Conclusions: Twelve weeks of brief intense interval exercise improved indices of cardiometabolic health to the same extent as traditional endurance training in sedentary men, despite a five-fold lower exercise volume and time commitment.
Article
The effectiveness of high-intensity interval training (HIIT) in inducing positive physiological adaptations is well documented. However, its impact on perceptual responses and on future physical activity (PA) engagement is less evaluated. The present study aimed to examine the effects of HIIT frequency on perceptual responses, health-related quality of life (HRQOL), and its influence in future PA participation. Thirty-five inactive adults were randomly assigned to a control (CON) and to 2 training groups that performed HIIT (10 × 60 s cycling, ∼83% peak power output) for 2 (HIIT-2) or 3 (HIIT-3) times per week for 8 weeks. Following the HIIT intervention, exercise enjoyment, HRQOL, and the intention to implement HIIT in the future were evaluated. Eight weeks after cessation of training, follow-up evaluations of HRQOL and PA were performed. Following the intervention, both training frequencies induced high levels of enjoyment (HIIT-2: 6.0 ± 1.1, HIIT-3: 6.0 ± 1.1, scale 1-7), improved HRQOL (HIIT-2: p = 0.040; HIIT-3: p = 0.024), and reported intention to implement HIIT in the future (HIIT-3: 100%, HIIT-2: 93% of participants). At follow-up, HIIT-3 participants reported higher completion of HIIT compared with HIIT-2 and CON (p < 0.05). Both training groups sustained improved HRQOL and increased vigorous and total PA (p < 0.05). This study showed that performing HIIT either 2 or 3 times per week is an enjoyable exercise modality that promotes a sustainable increase in habitual PA levels and improves HRQOL. Moreover, the higher training frequency resulted in greater HIIT completion in the 8-week period following the cessation of training.
Article
The effects of high intensity interval training (HIIT) frequency on cardiometabolic health and quality of life were examined in 35 healthy inactive adults (age: 31.7±2.6 yrs, VO2peak: 32.7±7.4 ml·kg−1 ·min−1). Participants were randomly assigned to a control (CON) and two training groups, which performed 10×60-s cycling at ~83% of peak power, two (HIIT-2) or three times per week (HIIT-3) for eight weeks. Compared with CON, both training regimes resulted in similar improvements in VO2peak (HIIT-2: 10.8%, p=0.048, HIIT-3: 13.6%, p=0.017), waist circumference (HIIT-2: -1.4 cm, p=0.048, HIIT-3: -2.4 cm, p=0.028), thigh cross-sectional area (HIIT-2: 11.4 cm2, p=0.001, HIIT-3: 9.3 cm2, p=0.001) and the physical health component of quality of life (HIIT-2: 8.4, p=0.001, HIIT-3: 12.2, p=0.001). However, HIIT-3 conferred additional health-related benefits by reducing total body and trunk fat percentage (p<0.05, compared with CON), total cholesterol and low-density lipoprotein-cholesterol (p<0.02, compared with CON) and by improving the mental component of quality of life (p=0.045, compared with CON). In conclusion, performing HIIT only twice per week is effective in promoting cardiometabolic health-related adaptations and quality of life in inactive adults. However, higher HIIT frequency is required for an effect on fat deposits, cholesterol and mental component of well-being.
Article
Purpose: Recent meta-analyses indicate that sprint interval training (SIT) improves cardiorespiratory fitness (V[Combining Dot Above]O2max), but the effects of various training parameters on the magnitude of the improvement remain unknown. The present meta-analysis examined the modifying effect of the number of sprint repetitions in a SIT session on improvements in V[Combining Dot Above]O2max. Methods: The databases PubMed and Web of Science were searched for original studies that have examined pre- and post-training V[Combining Dot Above]O2max in adults following ≥2 weeks of training consisting of repeated (≥2) Wingate-type cycle sprints, published up to 1 May 2016. Articles were excluded if they were not in English, involved patients, athletes, or participants with a mean baseline V[Combining Dot Above]O2max of >55 mL·kg·min or a mean age <18 years, and if a SIT trial was combined with another intervention or used intervals shorter than 10 s. A total of 38 SIT trials from 34 studies were included in the meta-analysis. Probabilistic magnitude-based inferences were made to interpret the outcome of the analysis. Results: The meta-analysis revealed a likely large effect of a typical SIT intervention on V[Combining Dot Above]O2max (mean ± 90 CL %: 7.8% ± 4.0%) with a possibly small modifying effect of the maximum number of sprint repetitions in a training session (-1.2 ± 0.8% decrease per 2 additional sprint repetitions). Apart from possibly small effects of baseline V[Combining Dot Above]O2max and age, all other modifying effects were unclear or trivial. Conclusion: We conclude that the improvement in V[Combining Dot Above]O2max with SIT is not attenuated with fewer sprint repetitions, and possibly even enhanced. This means that SIT protocols can be made more time-efficient, which may help SIT to be developed into a viable strategy to impact public health.
Article
Background: Over 41,000 people were diagnosed with colorectal cancer (CRC) in the UK in 2011. The incidence of CRC increases with age. Many elderly patients undergo surgery for CRC, the only curative treatment. Such patients are exposed to risks, which increase with age and reduced physical fitness. Endurance-based exercise training programmes can improve physical fitness, but such programmes do not comply with the UK, National Cancer Action Team 31-day time-to-treatment target. High-intensity interval training (HIT) can improve physical performance within 2-4 weeks, but few studies have shown HIT to be effective in elderly individuals, and those who do employ programmes longer than 31 days. Therefore, we investigated whether HIT could improve cardiorespiratory fitness in elderly volunteers, age-matched to a CRC population, within 31 days. Methods: This observational cohort study recruited 21 healthy elderly participants (8 male and 13 female; age 67 years (range 62-73 years)) who undertook cardiopulmonary exercise testing before and after completing 12 sessions of HIT within a 31-day period. Results: Peak oxygen consumption (VO2 peak) (23.9 ± 4.7 vs. 26.2 ± 5.4 ml/kg/min, p = 0.0014) and oxygen consumption at anaerobic threshold (17.86 ± 4.45 vs. 20.21 ± 4.11 ml/kg/min, p = 0.008) increased after HIT. Conclusions: It is possible to improve cardiorespiratory fitness in 31 days in individuals of comparable age to those presenting for CRC surgery.