Patricia V. Marco A. Author information Copyright and License information Disclaimer. Email: xm. Copyright in this article, its metadata, and any supplementary data is held by its author or authors. It is published under the Creative Commons Attribution By licence. This article has been cited by other articles in PMC. Methods: The RER, O 2 uptake and blood lactate were measured in eight endurance trained and eight untrained men age, Results: Endurance trained men presented higher O 2 uptake, lower blood lactate concentrations and lower RER values than those in untrained men at the three similar relative workloads.
Conclusions: These data demonstrate that RER measurement under sub-maximum exercise conditions was well correlated with other established physical fitness indicators, despite training condition.
Keywords: anaerobic threshold, physiological steady state, oxidative metabolism. Methods Participants Sixteen healthy male subjects volunteered for the study. Table 1. Open in a separate window. Unpaired student- t test. Experimental design The evaluations were done between and h in 6 sessions, after 10—12 h overnight fasting and 8—9 h of sleep. Anthropometric measures Two expert anthropometrists, using an anthropometric kit Rosscraft Tom Kit, Canada and following the International Society of Advancement in Kinanthropometry ISAK technique as described by Norton and Olds Norton and Olds, , performed the measurements and assessed body fat.
Diet study The food intake was assessed for three sequential days one during the weekend by the hour dietary record method. Blood lactate assay Capillary blood samples were taken from the fingertip with a heparinized capillary glass tube. Results As expected, all the physical fitness variables: body fat, VO 2max , workload max and lactate threshold measured as watts and VO 2 were significantly different in trained subjects compared to untrained Table 1. Figure 1. Figure 3. Table 2.
Food intake 1. Table 3. Workload during exercise at three different intensities. Table 4. Table 5. Discussion In the present study, we assessed the RER in trained and physically active untrained fasted men exercising at three different submaximal intensities. Conclusions Trained subjects showed higher oxidative metabolism and lower RER values than the untrained subjects, even when exercising at similar relative submaximal workloads.
Lineaments for Future Investigations The main obstacle of this study was to maintain working all our subjects more than 4 min above of the LT. Figure 2. Footnotes Competing Interests The authors declare that they have no competing interests. Heart Rate Monitoring: Applications and Limitations. Sports Med. Improved detection of lactate threshold during exercise using a log-log transformation.
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Are the effects of training on fat metabolism involved in the improvement of performance during high-intensity exercise? Muscle fatty acid oxidative capacity is a determinant of whole body fat oxidation in elderly people. Submaximal exercise testing: clinical application and interpretation. Physical Therapy. Anthropometrica: A textbook of body measurement for sports and health courses.
A perspective on fat intake in athletes. Coll Nutr. Muscle fat oxidative capacity is not impaired by age but by physical inactivity: association with insulin sensitivity.
Impact of aerobic exercise training on age-related changes in insulin sensitivity and muscle oxidative capacity. Indirect calorimetry: methodological and interpretative problems. The entire exercise bout lasted approximately 20 min. RPE was recorded, and HR was measured at the end of each interval; and an average of the ten s exercise intervals was used for statistical analysis. Data obtained from the strength assessment were used to determine an appropriate weight load for the HIRT session.
Exercises were performed in the following order: leg press and bench press York Barbell Co. Subjects performed a self-selected warm-up prior to starting. There was a rest period of 2. The average length of HIRT sessions was approximately 25 min.
HR was measured at the end of each set, and RPE was recorded at the end of each exercise; the average of HR and RPE of each of the six exercises was used in the statistical analyses. The gas analysis was performed via a mouthpiece and hose immediately prior to each exercise session, for 15 min, to obtain resting measures base.
Immediately after the conclusion of the exercise sessions, participants were seated and reconnected to the metabolic cart for 15 min to obtain immediately post- IP exercise measures.
The participants were then disconnected from the cart and remained quietly seated. Measurements were taken again during minutes 25 to 35 30 min and 50 to 60 60 min. A one-way repeated measures ANOVA was performed to determine baseline differences in salivary estradiol and cortisol levels. Initial models included fixed effects for nutritional treatment CHO vs. HIIT vs. HIRT , time baseline vs. IP vs. The three-way interaction was tested first; if non-significant, a reduced model was fit without the three-way interaction.
Multiple degree of freedom contrasts were then used to test for any evidence of differences between nutritional interventions or exercise modalities over time.
Only if those overall contrasts were significant, pairwise comparisons were completed. While this p value was not significant, the concentrations obtained were physiologically different between and within subjects. Concentrations spanned from 0.
Respiratory exchange ratio as a result of A modality and time and B treatment and time. Previous research evaluating the effect of AEE, HIIT, and HIRT individually on energy expenditure and energy substrate utilization have failed to provide direct comparisons between exercise modes; as well as failing to evaluate these effects in women.
The current study is the first to compare common exercise modalities, with acute nutritional intake, on post-exercise REE and RER in women. In the current study, ingesting PRO prior to exercise produced an increased post-exercise resting energy expenditure, compared to CHO consumption.
PRO ingestion also resulted in significantly augmented fat utilization 30 and 60 min post exercise. Perhaps the difference in exercise intensities for the two sessions was not substantial enough to elicit significant differences, such as those found in the current study. Additionally, it is unclear if differences between exercise intensities were controlled for [ 7 ]. However, single bouts of resistance training and running performed at the same intensity have both resulted in elevated REE up to 10 h post exercise [ 26 ].
Post-exercise REE data from the current study eludes to exercise intensity, instead of duration, as the primary determinant of EPOC variance, similar to several studies [ 4 - 6 ].
This is similar to previous findings [ 13 , 14 ] that demonstrate greater post-exercise REE and fat oxidation following a pre-exercise meal or snack with higher PRO content. In women, higher PRO diets have elicited an increased effect on diet-induced EE, in comparison to a lower PRO diet [ 28 , 29 ], which may be explained by amino acid absorption and disposal costs [ 29 ].
Consuming an additional kcal of PRO prior to exercise, as done in the current study, may increase EE up to an hour after exercise. Exercise intensity has previously been shown to be a driving factor for energy substrate utilization during and after exercise. Similar to the current study, previous studies have reported a significantly lower RER post exercise with repeated bouts of moderate intensity cycling, compared to a single bout [ 12 ] and a lower RER with a lower vs.
Previous data demonstrates differing exercise intensity can augment post-exercise REE and fat oxidation, but intervals do not produce differences compared to continuous exercise if total EE, duration, and intensity between the two remain the same throughout the exercise bout. Although diets were kept constant, residual effects of pre-exercise meals could cause similar RER values, since a fasting period of only 2 h was implemented prior to exercise.
During the post-exercise period, oxygen consumption is elevated for a period of time as a result of homeostasis disruption caused by exercise.
Physiological changes, such as those in cellular ion concentrations, tissue temperatures, and metabolite and hormone levels, take place into recovery, disabling oxygen consumption to lower back to resting levels [ 24 ]. This process of EPOC is related to exercise duration and intensity and can be influenced by sex-based hormones estrogen and macronutrient availability, among other things [ 24 ].
CHO is the primary fuel used during moderate- to high-intensity exercise; but post exercise, the body shifts from CHO to lipid energy sources, which lowers RER [ 30 ]. The current study demonstrates the fuel shift within 25 min post exercise, indicating greater post-exercise fat utilization with HIIT.
Little research has compared RER between aerobic and resistance training, but investigations that have been done present conflicting results. Similar to the current study, a lower RER was demonstrated 22 h after HIRT compared to more traditional resistance training four sets of 8 to 12 repetitions, 1- to 2-min rest [ 8 ].
In relation to sex, no differences were reported in post-circuit weight training RER between men and women [ 32 ]. It is important to examine the menstrual cycle due to the effects estrogen may have on energy substrate utilization, as the mid-luteal phase is characterized by high estrogen levels, which can enhance lipid utilization with exercise in women [ 19 , 33 ]. Similarly, higher fat oxidation has been reported with a low CHO diet compared to a moderate CHO diet at 1 h post exercise [ 14 ].
Substrate oxidation can be influenced by substrate availability from dietary intake and physical activity. While this study only evaluated acute feedings, low CHO diets have been shown to decrease circulating insulin levels, which promotes fatty acid utilization in skeletal muscle [ 14 ], perhaps supporting the lower RER for PRO ingestion in the current study.
Chronic dietary manipulations have an impact on substrate utilization. Based on 3-day diet logs, participants consumed on average Interestingly, while average PRO intake was relatively high, an additional acute feeding of 25 g of PRO significantly augmented REE in the current study, perhaps supporting the suggestion that higher protein needs 1. While the importance of chronic dietary manipulations is apparent, the current study supports the benefit of acute PRO feedings on EE, in healthy women eating within dietary guidelines.
Acute pre-exercise feedings have positively influenced fat oxidation, in comparison to a fasted state that blunted fat oxidation [ 16 ]. Future long-term studies identifying the acute effects on weight loss and body composition improvements in women would be valuable. A limitation in the current study was the use of indirect calorimetry to measure REE and RER, rather than whole body direct calorimetry, which is considered the gold standard.
However, because no modifications were made, the study results may be more practical for a woman who only wants to change her pre-workout nutrition rather than her whole diet. In addition, since this was an acute intervention, and post-exercise measurements were only conducted for 60 min, it is difficult to predict longer term EE and energy substrate utilization.
Specifically, EE calculations extrapolate our min findings to a h period using Weir et al. Future research should focus on determining the effects of chronic exercise and nutrition modifications in women using whole body calorimetry.
Specifically in women, this strategy may have positive implications on their health, weight, and body composition. Overweight, obesity, and weight loss [Internet]. Eating disorders: body image and advertising [Internet]. Healthy Place. Google Scholar. The effect of exercise intensity and duration on the oxygen deficit and excess post-exercise oxygen consumption. Smith J, Naughton LM. The effects of intensity of exercise on excess postexercise oxygen consumption and energy expenditure in moderately trained men and women.
Postexercise fat oxidation: effect of exercise duration, intensity, and modality. CAS Google Scholar. Metabolic response of different high-intensity aerobic interval exercise protocols. J Strength Cond Res. Article Google Scholar. High-intensity interval resistance training HIRT influences resting energy expenditure and respiratory ratio in non-dieting individuals. J Transl Med [Internet].
Journal of Translational Medicine; Jan [cited Jan 22];10 1 Effect of exercise intensity and duration on postexercise energy expenditure. Med Sci Sports Exerc. Effect of resistance training on excess post-exercise oxygen consumption. RER measurements are very sensitive to small errors in CO 2 readings from the gas analyzer.
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Skip to main content. Page Sections. Related Applications. Signal Overview RER is typically measured by sampling gas being expired by a person or animal and comparing how the ratio of O 2 and CO 2 compares to that of the surrounding air. Metabolic Human Exercise Physiology. Enabling Discovery.
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