Metabolic Differences During Submaximal, Steady-State Aerobic Exercise between Sarcopenic and Non-Sarcopenic Older Adults
Bibliographic record
Abstract
To examine differences in metabolic flexibility during submaximal aerobic exercise in sarcopenic (S) and non-sarcopenic (NS) older adults. Twenty-two older adults (mean age ± SE = 77 ± 2) were categorized as NS (n = 11) and S (n = 11) based on grip strength and muscle mass. Participants completed an aerobic, steady-state 10-min walk on a treadmill at 50 – 60% of their estimated V̇O2 max. Indirect calorimetry was assessed at baseline (fasted) and during the treadmill test to analyze respiratory quotient (RQ), carbohydrate (CHO) oxidation and fat oxidation, and % contributions of CHO and fat oxidation to energy expenditure (%CHO and %FAT, respectively). Two-way mixed factorial ANOVAS (time x group) and follow up t-tests were used to examine between group differences. At baseline, RQ was higher (0.76 ± 0.01 vs. 0.72 ± 0.01, p = 0.025) and fat oxidation was lower (0.08 ± 0.01 vs. 0.11 ± 0.01 g · min−1, p = 0.003) in S than NS individuals. The S group had significantly greater %CHO versus %FAT from 6 – 10 min of exercise (p = 0.005–0.014), whereas NS individuals maintained an approximately equal distribution of %CHO and %FAT until 8 – 10 min (p = 0.034–0.047). RQ (0.90 ± 0.06 vs. 0.86 ± 0.01, p = 0.039) and %CHO (70% vs. 57%, p = 0.046) were greater in S compared to NS at 8 min of exercise. Fat oxidation was consistently higher in NS than S individuals from 4 - 10 of min exercise (p = 0.016–0.045). Since skeletal muscle utilizes a large amount of energy during exercise, metabolic flexibility is key to efficiently utilize both CHO and fat sources to generate energy to match metabolic demands. Our data reveals that NS individuals were able to rely on both fuel sources during submaximal exercise indicating metabolic flexibility. Typically, exercising at 50 – 60% V̇O2 max utilizes 50% CHO and 50% fat contributions to energy expenditure, as observed in NS individuals. On the other hand, in S individuals, CHO composed a much larger proportion of total energy usage during exercise. These findings suggest that S individuals have low metabolic flexibility with higher dependence on CHO for energy during low-moderate aerobic activity. This study was funded by Abbott Nutrition.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".