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Modified sprint interval training protocols. Part II. Psychological responses.
Townsend, LK, Islam, H, Dunn, E, Eys, M, Robertson-Wilson, J, Hazell, TJ
Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. 2017;(4):347-353
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Abstract
Sprint-interval training (SIT) is a viable method to improve health and fitness. However, researchers have questioned the utility of SIT because of its strenuous nature. The current study aimed to determine if manipulating the sprint and recovery duration, while maintaining the 1:8 work to rest ratio, could uncover a more favourable SIT protocol. Nine healthy active males (age, 23.3 ± 3.0 years; body mass index, 22.4 ± 2.2 kg·m-2; maximal oxygen consumption, 48.9 ± 5.3 mL·kg-1·min-1) participated in 3 experimental running SIT sessions: (i) 30:240 (4 × 30-s efforts, 240-s recovery), (ii) 15:120 (8 × 15-s efforts, 120-s recovery), (iii) 5:40 (24 × 5-s efforts, 40-s recovery), and (iv) a final behavioural choice follow-up session. Affect, intentions, task self-efficacy, enjoyment, and preference were evaluated. Midway through exercise, affect became more positive for 5:40 compared with 30:240 (p < 0.05) and postexercise affect was greater for both 5:40 (p = 0.014) and 15:120 (p = 0.015) compared with 30:240. Participants expressed greater intentions to perform 5:40 3 and 5 times/week compared with 15:120 and 30:240 (p < 0.05). Participants felt more confident in their ability to perform 5:40 (p = 0.001) and 15:120 (p = 0.008) compared with 30:240. The 5:40 session was also rated as more enjoyable than 15:120 (p = 0.025) and 30:240 (p = 0.026). All participants preferred the 5:40 protocol. These data suggest that shorter sprints with more repetitions are perceived as more enjoyable and lead to greater intentions to engage in SIT.
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Comparison of Two Continuous Glucose Monitoring Systems, Dexcom G4 Platinum and Medtronic Paradigm Veo Enlite System, at Rest and During Exercise.
Taleb, N, Emami, A, Suppere, C, Messier, V, Legault, L, Chiasson, JL, Rabasa-Lhoret, R, Haidar, A
Diabetes technology & therapeutics. 2016;(9):561-7
Abstract
BACKGROUND Despite technological advances, the accuracy of continuous glucose monitoring (CGM) systems may not always be satisfactory with rapidly changing glucose levels, as is notable during exercise. We compare the performance of two current and widely used CGM systems, Dexcom G4 Platinum (Dexcom) and Medtronic Paradigm Veo Enlite system (Enlite), during both rest and exercise in adults with type 1 diabetes (T1D). RESEARCH DESIGN AND METHODS Paired sensor and plasma glucose (PG) values (total of 431 data pairs for Dexcom and 425 for Enlite) were collected from 17 adults (37.3 ± 13.6 years) with T1D. To evaluate and compare the accuracy of sensor readings, criteria involving sensor bias (sensor minus PG levels), absolute relative difference (ARD), and percentage of readings meeting International Organization for Standardization (ISO) criteria were considered. RESULTS Both Dexcom and Enlite performed equally well during the rest period, with respective mean/median biases of -0.12/-0.02 mmol/L versus -0.18/-0.40 (P = 0.78, P = 0.66) mmol/L and ARDs of 13.77/13.34% versus 12.38/11.95% (P = 0.53, P = 0.70). During exercise, sensor bias means/medians were -0.40/-0.21 mmol versus -0.26/-0.24 mmol/L (P = 0.67, P = 0.62) and ARDs were 22.53/15.13% versus 20.44/14.11% (P = 0.58, P = 0.68) for Dexcom and Enlite, respectively. Both sensors demonstrated significantly lower performance during exercise; median ARD comparison at rest versus exercise for both Dexcom and Enlite showed a P = 0.02. More data pairs met the ISO criteria for Dexcom and Enlite at rest, 73.6% and 76.9% compared with exercise 48.2% and 53.9%. CONCLUSION Dexcom and Enlite demonstrated comparable overall performances during rest and physical activity. However, a lower accuracy was observed during exercise for both sensors, necessitating a fine-tuning of their performance with physical activity.
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Higher resting-state activity in reward-related brain circuits in obese versus normal-weight females independent of food intake.
Hogenkamp, PS, Zhou, W, Dahlberg, LS, Stark, J, Larsen, AL, Olivo, G, Wiemerslage, L, Larsson, EM, Sundbom, M, Benedict, C, et al
International journal of obesity (2005). 2016;(11):1687-1692
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Abstract
BACKGROUND In response to food cues, obese vs normal-weight individuals show greater activation in brain regions involved in the regulation of food intake under both fasted and sated conditions. Putative effects of obesity on task-independent low-frequency blood-oxygenation-level-dependent signals-that is, resting-state brain activity-in the context of food intake are, however, less well studied. OBJECTIVE To compare eyes closed, whole-brain low-frequency BOLD signals between severely obese and normal-weight females, as assessed by functional magnetic resonance imaging (fMRI). METHODS Fractional amplitude of low-frequency fluctuations were measured in the morning following an overnight fast in 17 obese (age: 39±11 years, body mass index (BMI): 42.3±4.8 kg m-2) and 12 normal-weight females (age: 36±12 years, BMI: 22.7±1.8 kg m-2), both before and 30 min after consumption of a standardized meal (~260 kcal). RESULTS Compared with normal-weight controls, obese females had increased low-frequency activity in clusters located in the putamen, claustrum and insula (P<0.05). This group difference was not altered by food intake. Self-reported hunger dropped and plasma glucose concentrations increased after food intake (P<0.05); however, these changes did not differ between the BMI groups. CONCLUSION Reward-related brain regions are more active under resting-state conditions in obese than in normal-weight females. This difference was independent of food intake under the experimental settings applied in the current study. Future studies involving males and females, as well as utilizing repeated post-prandial resting-state fMRI scans and various types of meals are needed to further investigate how food intake alters resting-state brain activity in obese humans.
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Effects of an acute bout of aerobic exercise on immediate and subsequent three-day food intake and energy expenditure in active and inactive pre-menopausal women taking oral contraceptives.
Rocha, J, Paxman, J, Dalton, C, Winter, E, Broom, D
Appetite. 2015;:183-91
Abstract
UNLABELLED This study examined the effects of an acute bout of exercise of low-intensity on food intake and energy expenditure over four days in women taking oral contraceptives. Twenty healthy, active (n = 10) and inactive (n = 10) pre-menopausal women taking oral contraceptives completed two conditions (exercise and control), in a randomised, crossover fashion. The exercise experimental day involved cycling for one hour at an intensity equivalent to 50% of maximum oxygen uptake and two hours of rest. The control condition comprised three hours of rest. Participants arrived at the laboratory fasted overnight; breakfast was standardised and an ad libitum pasta lunch was consumed on each experimental day. Participants kept a food diary to measure food intake and wore an Actiheart to measure energy expenditure for the remainder of the experimental days and over the subsequent 3 days. There was a condition effect for absolute energy intake (exercise vs. CONTROL 3363 ± 668 kJ vs. 3035 ± 752 kJ; p = 0.033, d = 0.49) and relative energy intake (exercise vs. CONTROL 2019 ± 746 kJ vs. 2710 ± 712 kJ; p <0.001, d = -1.00) at the ad libitum lunch. There were no significant differences in energy intake over the four days in active participants and there was a suppression of energy intake on the first day after the exercise experimental day compared with the same day of the control condition in inactive participants (mean difference = -1974 kJ; 95% CI -1048 to -2900 kJ, p = 0.002, d = -0.89). There was a group effect (p = 0.001, d = 1.63) for free-living energy expenditure, indicating that active participants expended more energy than inactive participants during this period. However, there were no compensatory changes in daily physical activity energy expenditure. These results support the use of low-intensity aerobic exercise as a method to induce a short-term negative energy balance in inactive women taking oral contraceptives.
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Effect of varying rest intervals between sets of assistance exercises on creatine kinase and lactate dehydrogenase responses.
Machado, M, Koch, AJ, Willardson, JM, Pereira, LS, Cardoso, MI, Motta, MK, Pereira, R, Monteiro, AN
Journal of strength and conditioning research. 2011;(5):1339-45
Abstract
To examine the effects of different rest intervals between sets on serum creatine kinase (CK) and lactate dehydrogenase (LDH) activity, 10 men (age = 25.6 ± 2.2 years, height = 173.1 ± 7.1 cm, and body mass = 75.9 ± 10.0 kg) participated in a randomized within-subject design that involved 4 resistance exercise sessions. Each session consisted of 4 sets of 10 repetitions with 10 repetition maximum loads for the chest press, pullover, biceps curl, triceps extension, leg extension, and prone leg curl. The sessions differed only in the length of the rest interval between sets and exercises, specifically: 60, 90, 120, 180 seconds. Serum CK and LDH were significantly (p < 0.05) elevated 24-72 hours after each session, with no significant differences between rest intervals (p = 0.94 and p = 0.99, respectively). The mechanical stress imposed by the 4 resistance exercise sessions invoked similar damage to the muscle fibers independent of the rest interval between sets. These data indicate that the accumulated volume of work is the primary determinant of muscle damage in trained subjects who are accustomed to resistance exercise with short rest intervals.
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Muscle metabolism and performance improvement after two training programmes of sprint running differing in rest interval duration.
Saraslanidis, P, Petridou, A, Bogdanis, GC, Galanis, N, Tsalis, G, Kellis, S, Mougios, V
Journal of sports sciences. 2011;(11):1167-74
Abstract
Repeated-sprint training often involves short sprints separated by inadequate recovery intervals. The effects of interval duration on metabolic and performance parameters are unclear. We compared the effects of two training programmes, differing in rest interval duration, on muscle (vastus lateralis) metabolism and sprint performance. Sixteen men trained three times a week for 8 weeks, each training session comprising 2-3 sets of two 80-m sprints. Sprints were separated by 10 s (n = 8) or 1 min (n = 8). Both training programmes improved performance in the 100-, 200-, and 300-m sprints, but the improvement was greater in the 10-s group during the final 100 m of the 200- and 300-m runs. Independent of interval duration, training mitigated the drop of muscle ATP after two 80-m sprints. The drop in phosphocreatine and the increases in glucose-6-phosphate and fructose-6-phosphate after two 80-m sprints were greater in the 10-s group. In conclusion, training with a limited number of repeated short sprints (≤10 s) may be more effective in improving speed maintenance in 200- and 300-m runs when performed with a 1:1 rather than a 1:6 exercise-to-rest ratio. This may be due to a greater activation of glycolysis caused, in part, by the limited resynthesis of phosphocreatine during the very short rest interval.
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The effects of magnesium supplementation on thyroid hormones of sedentars and Tae-Kwon-Do sportsperson at resting and exhaustion.
Cinar, V
Neuro endocrinology letters. 2007;(5):708-12
Abstract
The effect of magnesium on thyroid hormones of sedentars and sportsperson in Tae-Kwon-Do, has been investigated in a 4-weeks training program. Group 1 consisted of sedentars receiving 10 mg/kg/day Mg for 4 weeks. Group 2 consisted of subjects receiving magnesium (Mg) supplement and practicing Tae-Kwon-Do for 90-120 min/day, for five days a week. Group 3 consisted of subjects practicing Tae-Kwon-Do but receiving Mg supplements. TSH levels increased with training and Mg supplementation (p<0.05). Mg increased FT3 values. (p<0.05). TT3 values of groups reduced in all groups (p<005). After supplementation, group 1 had higher TT4 values than groups 1 and 3 and the group 2 had higher TT4 values than the third group (p<005). Results of this research show that training until exhaustion causes reduction in thyroid hormone activity in sedentars and sportsperson. It has been established that Mg supplementation however, prevents reduction in thyroid hormone activity in sedentars and sportsperson.
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Thermic effect of food and beta-adrenergic thermogenic responsiveness in habitually exercising and sedentary healthy adult humans.
Stob, NR, Bell, C, van Baak, MA, Seals, DR
Journal of applied physiology (Bethesda, Md. : 1985). 2007;(2):616-22
Abstract
The thermic effect of food (TEF) is an important physiological determinant of total daily energy expenditure (EE) and energy balance. TEF is believed to be mediated in part by sympathetic nervous system activation and consequent beta-adrenergic receptor (beta-AR) stimulation of metabolism. TEF is greater in habitually exercising than in sedentary adults, despite similar postprandial sympathetic nervous system activation. We determined whether augmented TEF in habitually exercising adults is associated with enhanced peripheral thermogenic responsiveness to beta-AR stimulation. In separate experiments in 22 sedentary and 29 habitually exercising adults, we measured the increase in EE (indirect calorimetry, ventilated hood) during beta-AR stimulation (intravenous isoproterenol: 6, 12, and 24 ng x kg fat-free mass(-1) x min(-1)) and EE before and after a liquid meal (40% of resting EE; 53% carbohydrate, 32% fat, 15% protein). The increase in EE during incremental isoproterenol administration was greater (P = 0.01) in habitual exercisers (0.34 +/- 0.03, 0.54 +/- 0.04, 0.81 +/- 0.05 kJ/min; means +/- SE) than in sedentary adults (0.26 +/- 0.03, 0.40 +/- 0.03, 0.64 +/- 0.04 kJ/min). The area under the TEF response curve was also greater (P = 0.04) in habitual exercisers (160 +/- 9 kJ) than in sedentary adults (130 +/- 11 kJ) and was positively related to beta-AR thermogenic responsiveness (r = 0.32, P = 0.02). We conclude that TEF is related to beta-AR thermogenic responsiveness and that the greater TEF in habitual exercisers is attributable in part to their augmented beta-AR thermogenic responsiveness. Our results also suggest that peripheral thermogenic responsiveness to beta-AR stimulation is a physiological determinant of TEF and hence energy balance in healthy adult humans.
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Effects of dietary caffeine on mood when rested and sleep restricted.
James, JE, Gregg, ME
Human psychopharmacology. 2004;(5):333-41
Abstract
Prolonged use of caffeine can lead to physical dependence evidenced by characteristic withdrawal symptoms during abstinence. Debate exists as to whether mood enhancement by caffeine represents a net effect or merely the restoration of abstinence-induced mood decrements. One aim of this study was to determine the net effects on mood of dietary caffeine compared with prolonged abstinence. In addition, the study aimed to determine whether caffeine restores mood degraded by a non-caffeine source, namely, sleep restriction. A double-blind placebo-controlled cross-over design was employed in which 48 male and female volunteers alternated weekly between ingesting placebo and caffeine (1.75 mg/kg) three times daily for 4 consecutive weeks, while being either rested or sleep restricted. Mood was assessed using a computerized version of the profile of mood states (POMS), giving scores for overall mood and six mood dimensions. Gender had small effects on mood, whereas all mood dimensions were markedly adversely affected by sleep restriction. Caffeine had no significant net enhancing effects on mood when participants were rested, and produced no net restorative effects when mood was degraded by sleep restriction. On the contrary, caffeine-induced decrements in mood were observed during both conditions of rest and sleep restriction.
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Metabolic response to a large starch meal after rest and exercise: comparison between men and women.
Folch, N, Péronnet, F, Massicotte, D, Charpentier, S, Lavoie, C
European journal of clinical nutrition. 2003;(9):1107-15
Abstract
BACKGROUND Net whole-body and hepatic de novo lipogenesis could be more active in women than in men, but no comparison has been made between men and women in the two phases of the ovarian cycle after ingestion of a large carbohydrate meal. OBJECTIVE We hypothesized that net whole-body de novo lipogenesis could be larger in women than men, and that glycogen and fat balance could be, respectively, lower and higher, following a large pasta meal ingested after rest or exercise. DESIGN The metabolic response to a pasta meal (5 g dry weight/kg body mass) was studied in six men and six women (matched for age and BMI) in the follicular and luteal phases, following rest or exercise (90 min at 50% VO(2max)). Protein, glucose, and fat oxidation, and net whole-body de novo lipogenesis were computed for 10 h following ingestion of the meal using indirect respiratory calorimetry corrected for urea excretion. RESULTS No net whole-body de novo lipogenesis was observed in any group in any situation (postrest and postexercise). When the meal was ingested following exercise, fat oxidation was significantly higher and glucose oxidation was significantly lower (P<0.05) than following the period of rest, and in a given experimental situation, the respective contributions of protein, fat, and glucose oxidation to the energy yield were similar in men and women in both phases of the cycle. CONCLUSIONS The contribution of substrate oxidation to the energy expenditure as well as fat and glycogen balance, and the effect of a previous exercise period, were similar in men and women in both phases of the cycle following ingestion of the large carbohydrate meal.