L’homéostasie est régulée par l’équilibre entre l’alimentation et l’activité. Les dérèglements de cet équilibre, observés dans l’obésité (déséquilibre en faveur de l’alimentation avec sédentarité) ou ...l’anorexie mentale restrictive (déséquilibre en défaveur de l’alimentation avec activité physique soutenue), trouvent leur origine au niveau de la motivation. La motivation pour une récompense – mais pas la consommation qui s’ensuit – est dictée par l’activité des neurones dopaminergiques mésocorticolimbiques. Ceci est vrai pour pour des récompenses naturelles, telles que l’alimentation, le sexe ou les contacts sociaux, ainsi que pour les drogues d’abus. À l’inverse de ces récompenses, les bases neurobiologiques de la motivation pour l’exercice physique étaient jusqu’à récemment encore inconnues. La mise au point d’un protocole de conditionnement opérant (ratios fixes, ratios progressifs) permettant d’évaluer chez la souris la motivation pour l’activité physique, y compris dans une situation de choix avec la prise de nourriture, nous a conduits à l’identification du rôle clef des récepteurs CB1 localisés sur les terminaisons des neurones GABAergiques de l’aire tegmentale ventrale (l’origine des neurones dopaminergiques mésocorticolimbiques). La communication orale reprendra les résultats expérimentaux ayant permis cette identification avant d’exposer des résultats récents obtenus dans un modèle ayant une valeur translationnelle plus importante, i.e. le modèle « d’économie fermée ». Dans ce modèle, les souris vivent 24h/24 en autarcie dans une chambre régie par des comportements opérants, la prise de nourriture ou l’activité physique étant ainsi conditionnée à un effort préalable (prix à payer), dont la valeur augmente progressivement au cours du temps. Dans ce modèle, le rôle unique des récepteurs CB1 dans le striatum ventral sera ensuite rapidement évoqué.
Despite compelling evidence to the contrary, the view that oxygen uptake (V̇O
2
) increases linearly with exercise intensity (e.g., power output, speed) until reaching its maximum persists within the ...exercise physiology literature. This viewpoint implies that the V̇O
2
response at any constant intensity is predictable from a ramp-incremental exercise test. However, the V̇O
2
versus task-specific exercise intensity relationship constructed from ramp-incremental versus constant-intensity exercise are not equivalent preventing the use of V̇O
2
responses from 1 domain to predict those of the other. Still, this “linear” translational framework continues to be adopted as the guiding principle for aerobic exercise prescription and there remains in the sport science literature a lack of understanding of how to interpret V̇O
2
responses to ramp-incremental exercise and how to use those data to assign task-specific constant-intensity exercise. The objectives of this paper are to (i) review the factors that disassociate the V̇O
2
versus exercise intensity relationship between ramp-incremental and constant-intensity exercise paradigms; (ii) identify when it is appropriate (or not) to use ramp V̇O
2
responses to accurately assign constant-intensity exercise; and (iii) illustrate the technical and theoretical challenges with prescribing constant-intensity exercise solely on information acquired from ramp-incremental tests. Actual V̇O
2
data collected during cycling exercise and V̇O
2
kinetics modelling are presented to exemplify these concepts. Possible solutions to overcome these challenges are also presented to inform on appropriate intensity selection for individual-specific aerobic exercise prescription in both research and practical settings.
Exercise prescription to reverse frailty Bray, Nick W; Smart, Rowan R; Jakobi, Jennifer M ...
Applied physiology, nutrition and metabolism/Applied physiology, nutrition, and metabolism,
10/2016, Letnik:
41, Številka:
10
Journal Article
Recenzirano
Odprti dostop
Frailty is a clinical geriatric syndrome caused by physiological deficits across multiple systems. These deficits make it challenging to sustain homeostasis required for the demands of everyday life. ...Exercise is likely the best therapy to reverse frailty status. Literature to date suggests that pre-frail older adults, those with 1–2 deficits on the Cardiovascular Health Study-Frailty Phenotype (CHS-frailty phenotype), should exercise 2–3 times a week, for 45–60 min. Aerobic, resistance, flexibility, and balance training components should be incorporated but resistance and balance activities should be emphasized. On the other hand, frail (CHS-frailty phenotype ≥ 3 physical deficits) older adults should exercise 3 times per week, for 30–45 min for each session with an emphasis on aerobic training. During aerobic, balance, and flexibility training, both frail and pre-frail older adults should work at an intensity equivalent to a rating of perceived exertion of 3–4 (“somewhat hard”) on the Borg CR10 scale. Resistance-training intensity should be based on a percentage of 1-repetition estimated maximum (1RM). Program onset should occur at 55% of 1RM (endurance) and progress to higher intensities of 80% of 1RM (strength) to maximize functional gains. Exercise is the medicine to reverse or mitigate frailty, preserve quality of life, and restore independent functioning in older adults at risk of frailty.
Trait-based revision lies at the heart of this book as it's been at the heart of Ruth's career in writing instruction. Rethinking revision is what will ultimately help you to teach writing well. This ...book shows you how to assess and teach writing in a way that's practical and doable-and best of all-you'll see results.
Numerous studies have examined heart rate variability (HRV) and cardiac baroreceptor sensitivity (BRS) variables during recovery both acutely (under 3 h) and long-term (24, 48, and 72 h) ...postexercise. However, there is little literature examining HRV and BRS measures between these timepoints. Spontaneous short-term HRV and cardiac BRS measures were collected in 9 participants before and at zero, 1, 2, 4, 6, and 8 h after 3 separate conditions: moderate-intensity continuous exercise (MICE; 45 min at 50% heart rate reserve), high-intensity interval exercise (HIIE; 25 min including ten 1-min intervals at 85% heart rate reserve), and control (30 min quiet rest). HRV measures in the time domain were only affected immediately following HIIE and MICE at hour zero (all p < 0.043), whereas frequency-domain metrics were unaltered (all p > 0.102). These measures were highly consistent across the control day (all p > 0.420). Cardiac BRS was assessed via low-frequency (LF) gain, and revealed reductions following HIIE at hour zero (p < 0.012). Cardiac BRS LF gain remained consistent following MICE and control interventions (all p > 0.280). The common practice of waiting 12 to 24 h is overly conservative as the current findings demonstrate measures return to baseline at ∼60 min after exercise. Moreover, these metrics demonstrated high levels of within- and between-day reliability.
Novelty
Previously a 12-h minimum restriction from exercise was required before participation in HRV/BRS studies.
Recovery from moderate-intensity exercise for HRV and BRS metrics was <60 min; whereas, high-intensity intervals led to alterations for approximately 60 min.
Spontaneous HRV and cardiac BRS demonstrated high levels of within-day reproducibility.
The objective of this research is to explore the influence of different exercise protocols on fat oxidation.
Uncontrolled experimental study.
For this purpose, 10 sedentary male subjects were ...recruited, 30 to 39years old, with elevated body mass index (BMI). Each participant was evaluated in four separate sessions. The first session consisted in determining peak aerobic power (PAP). The following sessions participants performed three equivalent exercise protocols, consisting of each one in three bouts of 15-minute exercise separated by 5minutes of rest in between. The constant intensity protocol included exercise periods at 55% of PAP, while the other two (increasing and decreasing intensity protocols) consisted in exercise periods at 40, 55 and 70% of PAP in an increasing or decreasing order respectively.
There were no significant differences (P>0.05) in total caloric expenditure among the three protocols (range: 5.9±0.2 to 6.1±0.2 kcal·kg−1). DIP causes a progressive increase in fat oxidation comparative to IIP and CIP protocols (P<0.01). In period third of the protocols, DIP oxidized significantly more fat than the other two. The perception of effort was significantly lower in the DIP compared to the other two protocols (P<0.01).
Fat oxidation in exercises at intervals of different intensity depends on the order of these periods, being greater when performed decreasingly, as well as the perception of effort, being more useful for sedentary subjects with high BMI.
L’objectif de cette recherche est d’explorer l’influence de différents protocoles d’exercice sur l’oxydation des graisses.
Étude expérimentale non contrôlée.
Pour cela, dix sujets masculins sédentaires ont été recrutés, âgés de 30 à 39 ans, avec un indice de masse corporelle (IMC) élevé. Chaque participant a été évalué en quatre sessions distinctes. La première séance consistait à déterminer la puissance aérobie maximale (PAP). Les participants aux sessions suivantes ont exécuté trois protocoles d’exercices équivalents, consistant chacun en trois séances d’exercice de 15 minutes séparées par 5 minutes de repos entre les deux. Le protocole à intensité constante comprenait des périodes d’exercice à 55 % de PAP, tandis que les deux autres (protocoles à intensité croissante et décroissante) consistaient en des périodes d’exercice à 40, 55 et 70 % de PAP dans un ordre croissant ou décroissant respectivement.
Il n’y avait pas de différences significatives (p>0,05) dans la dépense calorique totale entre les trois protocoles (gamme : 5,9±0,2 à 6,1±0,2 kcal·kg−1). Le DIP provoque une augmentation progressive de l’oxydation des graisses par rapport aux protocoles IIP et CIP (p<0,01). Dans la troisième période des protocoles, le DIP a oxydé significativement plus de graisse que les deux autres. La perception de l’effort était significativement plus faible dans le DIP par rapport aux deux autres protocoles (p<0,01).
L’oxydation des graisses dans les exercices à des intervalles d’intensité différente dépend de l’ordre de ces périodes, étant plus grande lorsqu’elles sont effectuées de manière décroissante, ainsi que de la perception de l’effort, étant plus utile pour les sujets sédentaires avec un IMC élevé.
The Canadian Society for Exercise Physiology assembled a Consensus Panel representing national organizations, content experts, methodologists, stakeholders, and end-users and followed an established ...guideline development procedure to create the
. These guidelines underscore the importance of movement behaviours across the whole 24-h day. The development process followed the strategy outlined in the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument. A large body of evidence was used to inform the guidelines including 2 de novo systematic reviews and 4 overviews of reviews examining the relationships among movement behaviours (physical activity, sedentary behaviour, sleep, and all behaviours together) and several health outcomes. Draft guideline recommendations were discussed at a 4-day in-person Consensus Panel meeting. Feedback from stakeholders was obtained by survey (
= 877) and the draft guidelines were revised accordingly. The final guidelines provide evidence-based recommendations for a healthy day (24-h), comprising a combination of sleep, sedentary behaviours, and light-intensity and moderate-to-vigorous-intensity physical activity. Dissemination and implementation efforts with corresponding evaluation plans are in place to help ensure that guideline awareness and use are optimized.
First ever 24-Hour Movement Guidelines for Adults aged 18-64 years and Adults aged 65 years or older with consideration of a balanced approach to physical activity, sedentary behaviour, and sleep Finalizes the suite of 24-Hour Movement Guidelines for Canadians across the lifespan.
L’insuffisance d’activité physique (AP) et la sédentarité sont des facteurs de risques de nombreuses maladies et sont associées à une augmentation de la mortalité. Le rôle du médecin généraliste est ...central dans le repérage de ces deux facteurs de risque pour intervenir précocement dans la modification des comportements. Il existe de nombreux outils de mesure de l’AP validés mais ils sont difficilement utilisables en consultation. Un questionnaire court, en deux questions, le Brief Physical Activity Assessment Tool (BPAAT) ou questionnaire de Marshall, a été validé, en anglais, versus accélérométrie. Notre étude avait pour but de comparer la capacité du test de Marshall (dans sa version française) à classer les patients en suffisamment ou insuffisamment actifs, par rapport aux tests IPAQ et le GPAQ. Les objectifs secondaires étaient, d’évaluer la faisabilité de ce repérage en pratique de soins primaires et de tester trois autres approches : une autoévaluation par le patient de son AP ; une question sur l’inscription dans un club ou une association sportive, une question de repérage rapide de la sédentarité.
Étude épidémiologique transversale comparant une évaluation par le médecin avec le questionnaire de Marshall et les questions des trois autres approches à un questionnaire autorempli contenant les questionnaires IPAQ et GPAQ.
Quatre cents quatre-vingt-seize sujets ont été inclus. Le questionnaire de Marshall avec un seuil à trois permettait de classer correctement les patients en suffisamment actifs ou insuffisamment actifs avec 68,41 % de concordance par rapport à l’IPAQ, et avec 70,10 % de concordance par rapport au GPAQ. Une question d’autoévaluation de l’activité physique pourrait avoir une valeur discriminante proche du test de Marshall. Pour l’évaluation de la sédentarité, une simple question évaluant le niveau de sédentarité ressenti de 0 à 10 est utilisable en pratique. Les médecins étaient capables de repérer les patients insuffisamment actifs et/ou sédentaires dans plus du tiers de leurs consultations.
Insufficient physical activity (PA) and physical inactivity are risk factors for many diseases and are associated with increased mortality. The role of the general practitioner is central in identifying these two risk factors in order to intervene early in behavior modification. There are many validated PA measurement tools but they are difficult to use in consultation. A short questionnaire, in two questions, the Brief Physical Activity Assessment Tool (BPAAT) or Marshall questionnaire, was validated, in English, versus accelerometry. Our study aimed to compare the ability of the Marshall test (in its French version) to classify patients as sufficiently or insufficiently active, compared to the IPAQ and GPAQ tests. The secondary objectives were to assess the feasibility of this screening in primary care practice and to test three other approaches: patient self-assessment of their PA; a question about registering with a club or a sports association, a question of quickly identifying a sedentary lifestyle.
Cross-sectional epidemiological study comparing physician assessment with Marshall's questionnaire and questions from the other three approaches to a self-completed questionnaire containing the IPAQ and GPAQ questionnaires.
Fur hundred and ninety six subjects were included. The Marshall questionnaire with a threshold of three made it possible to correctly classify patients as sufficiently active or insufficiently active with 68.41% agreement with respect to the IPAQ, and with 70.10% agreement with respect to the GPAQ. A self-assessment question on physical activity could have a discriminating value close to the Marshall test. For the evaluation of sedentariness, a simple question evaluating the level of sedentariness felt from 0 to 10 is usable in practice. Doctors were able to identify insufficiently active and/or sedentary patients in more than a third of their consultations.
Expert guidelines recommend an aerobic cooldown to lower blood glucose for the management of post-exercise hyperglycemia. This strategy has never been empirically tested. Our aim in this study was to ...compare the glycemic effects of performing an aerobic cooldown vs not performing a cooldown after a fasted resistance exercise session. We hypothesized that the cooldown would lower blood glucose in the 30 minutes after exercise and would result in less time in hyperglycemia in the 6 hours after exercise.
Participants completed 2 identical resistance exercise sessions. One was followed by a low-intensity (30% of peak oxygen consumption) 10-minute cycle ergometer cooldown, and the other was followed by 10 minutes of sitting. We compared the changes in capillary glucose concentration during these sessions and continuous glucose monitoring (CGM) outcomes over 24 hours post-exercise.
Sixteen participants completed the trial. Capillary glucose was similar between conditions at the start of exercise (p=0.07). Capillary glucose concentration decreased by 0.6±1.0 mmol/L during the 10-minute cooldown, but it increased by 0.7±1.3 mmol/L during the same time in the no-cooldown condition. The resulting difference in glucose trajectory led to a significant interaction (p=0.02), with no effect from treatment (p=0.7). Capillary glucose values at the end of recovery were similar between conditions (p>0.05). There were no significant differences in CGM outcomes.
An aerobic cooldown reduces glucose concentration in the post-exercise period, but the small and brief nature of this reduction makes this strategy unlikely to be an effective treatment for hyperglycemia occurring after fasted exercise.
Les lignes directrices des experts préconisent une phase de récupération aérobie pour abaisser la glycémie et gérer l'hyperglycémie post-exercice. Cette stratégie n'a jamais été testée empiriquement. Notre objectif était de comparer les effets glycémiques de la mise en place d'une phase de récupération aérobie par rapport à l'absence de récupération après une séance d'exercice de résistance à jeun. Nous avons émis l'hypothèse que cette période de récupération abaisserait la glycémie dans les 30 minutes suivant l'exercice et réduirait la durée de l'hyperglycémie dans les 6 heures suivant l'exercice.
Les participants ont effectué deux séances identiques d'exercices de résistance. L'une était suivie d'une récupération aérobie sur ergocycle, à faible intensité, pendant 10 minutes (pic de VO2 30%), et l'autre était suivie de 10 minutes en position assise. Nous avons comparé les variations de la glycémie capillaire au cours de ces séances et les données de la surveillance continue du glucose (SCG) sur 24 heures après l'exercice.
Seize participants ont terminé l'étude. La glycémie capillaire était similaire entre les conditions au début de l'exercice (p=0.07). La valeur de glycémie capillaire a diminué de 0.6 ± 1.0 mmol/L pendant les 10 minutes de récupération, mais a augmenté de 0.7 ± 1.3 mmol/L pendant la même période dans la condition sans récupération. La différence observée dans le profil glycémique a conduit à une interaction significative (p=0.02) sans effet du traitement (p=0.7). Les valeurs de glycémie capillaire à la fin de la période de récupération étaient similaires entre les conditions (p>0.05). Il n'y avait pas de différences significatives dans les données de SCG.
Une phase de récupération aérobie réduit les concentrations de glucose dans la période post-exercice, mais la nature, brève et faible, de cette réduction rend cette stratégie peu susceptible d'être un traitement efficace contre une hyperglycémie survenant après un exercice à jeun.
Athletes in kayak sprint competitions often do several races successively with short time to recover. High performance training also involves daily training sessions with high volume and intensity. ...Cold is used in sports as a quick and easy recovery method therefore the current study's goal is to analyze the impact of a cooling vest in elite sprint kayakers’ recovery.
Ten elite sprint kayakers (age, 21.63±2.85years; height, 177.9±7.33cm; body mass, 75.18±7.33kg) completed, in kayak ergometer, on two days apart the same protocol except for the active rest, in which, randomly, in one of them they used a cold vest. Each moment was performed in a room with controlled temperature (20.93°C to 21.22°C) and humidity (66.04% to 68.90%), consisting in 15minutes of acclimatization, warm-up, 5 times 5minutes (at 75% maximal average power (MAP) in 4minutes test), 15minutes of active rest at 40% MAP, 15minutes of passive rest and finally a 500-m maximal test. On both moments it was determined, among others, the blood lactate concentration, the core temperature assessed by urine temperature and it was asked the rating of perceived exertion (Borg's RPE Scale) and recuperation (0 to 10 scale with 10 representing completely recovered).
There was no significant difference between the 500m maximal test in the two moments. However, the athlete's subjective perception of recovery was significantly higher with vest (P<0.01). The blood lactate concentration was significantly lower after the active recovery using the cold vest (P<0.05) as well as core temperature, 15minutes after the active rest (P<0.05).
Results suggest that the use of a cooling vest during active rest after training or competition can improve recovery. It has interest to test it in on-water situations.
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