bims-exemet 2021-08-01 papers

Issue of 2021–08–01
four papers selected by
Javier Botella Ruiz, Victoria University

Physiol Rep. 2021 Aug;9(15): e14962

Individual physiological and mitochondrial responses during 12 weeks of intensified exercise.

Macsue Jacques, Shanie Landen, Javier Alvarez Romero, Xu Yan, Andrew Garnham, Danielle Hiam, Mélina Siegwald, Emma Mercier, Anne Hecksteden, Nir Eynon, Sarah Voisin.

AIM: Observed effects of exercise are highly variable between individuals, and subject-by-training interaction (i.e., individual response variability) is often not estimated. Here, we measured mitochondrial (citrate synthetase, cytochrome-c oxidase, succinate dehydrogenase, and mitochondrial copy-number), performance markers (Wpeak , lactate threshold [LT], and VO2peak ), and fiber type proportions/expression (type I, type IIa, and type IIx) in multiple time points during 12-week of high-intensity interval training (HIIT) to investigate effects of exercise at the individual level.
METHODS: Sixteen young (age: 33.1 ± 9.0 years), healthy men (VO2peak 35-60 ml/min/kg and BMI: 26.4 ± 4.2) from the Gene SMART study completed 12-week of progressive HIIT. Performance markers and muscle biopsies were collected every 4 weeks. We used mixed-models and bivariate growth models to quantify individual response and to estimate correlations between variables.
RESULTS: All performance markers exhibited significant (Wpeak 0.56 ± 0.33 p = 0.003, LT 0.37 ± 0.35 p = 0.007, VO2peak 3.81 ± 6.13 p = 0.02) increases overtime, with subject-by-training interaction being present (95% CI: Wpeak 0.09-0.24, LT 0.06-0.18, VO2peak 0.27-2.32). All other measurements did not exhibit significant changes. Fiber type IIa proportions at baseline was significantly associated with all physiological variables (p < 0.05), and citrate synthetase and cytochrome-c oxidase levels at baseline and overtime (i.e., intercept and slope) presented significant covariance (p < 0.05). Finally, low correlations between performance and mitochondrial markers were observed.
CONCLUSION: We identified a significant subject-by-training interaction for the performance markers. While for all other measures within-subject variability was too large and interindividual differences in training efficacy could not be verified. Changes in measurements in response to exercise were not correlated, and such disconnection should be further investigated by future studies.

Keywords: VO2peak; exercise; mitochondria; training variability

DOI: https://doi.org/10.14814/phy2.14962

Nutrition. 2021 Jun 12. pii: S0899-9007(21)00251-3. [Epub ahead of print]91-92 111389

Basal and resistance exercise-induced increase in protein synthesis is impaired in skeletal muscle of iron-deficient rats.

Kazuhiko Higashida, Sachika Inoue, Nodoka Takeuchi, Satoru Ato, Riki Ogasawara, Naoya Nakai.

OBJECTIVES: We aimed to investigate the effect of iron deficiency on basal- and contraction-induced increases in muscle protein synthesis.
METHODS: Four-wk-old male Sprague-Dawley rats were divided into three groups. The rats in two of the three groups had free access to a control diet (AD) or iron-deficient diet (ID) for 4 wk. The rats in the third group (CON) were pair-fed the control diet to the mean intake of the ID group.
RESULTS: In comparison with the CON group, the ID group showed significantly lower hematocrit and hemoglobin concentrations, iron-containing protein levels, and total iron content in skeletal muscle, but non-iron-containing protein levels did not show any differences between the groups. Protein synthesis, measured by puromycin-labeled peptides, was lower in the ID group compared with the CON group in both basal- and contraction-stimulated states. The ID diet impaired the activation levels of signaling pathways involved in protein synthesis, such as ribosomal protein S6 and eukaryotic translation initiation factor 4E-binding protein 1. Furthermore, dietary iron deficiency decreased autophagy capacity, but did not affect the ubiquitinated protein content.
CONCLUSIONS: These results suggest that severe iron deficiency decreases not only basal but also muscle contraction-induced increases in protein synthesis due to, at least in part, downregulation of the protein synthesis signaling pathway in the skeletal muscle.

Keywords: Anemia; Autophagy; Eccentric contraction; Protein breakdown; mTOR

DOI: https://doi.org/10.1016/j.nut.2021.111389

Int J Sports Med. 2021 Jul 28.

Resistance training and HIIT improve cardiometabolic health in high risk older adults.

Kelly Ann McLeod, Matthew D Jones, Jeanette M Thom, Belinda J Parmenter.

Progressive resistance training (PRT) and high-intensity interval training (HIIT) improve cardiometabolic health in older adults. Whether combination PRT+HIIT (COMB) provides similar or additional benefit is less clear. This systematic review with meta-analysis of controlled trials examined effects of PRT, HIIT and COMB compared to non-exercise control in older adults with high cardiometabolic risk. Databases were searched until January 2021, with study quality assessed using the PEDro scale. Risk factor data was extracted and analysed using RevMan V.5.3. We analysed 422 participants from nine studies (7 PRT, n=149, 1 HIIT, n=10, 1 COMB, n=60; control n=203; mean age 68.1±1.4 years). Compared to control, exercise improved body mass index (mean difference (MD) -0.33 [-0.47, -0.20], p≤0.0001), body fat % (standardised mean difference (SMD) -0.71 [-1.34, -0.08], p=0.03), aerobic capacity (SMD 0.41 [0.05, 0.78], p=0.03), low-density lipoprotein (SMD -0.27 [-0.52, -0.01], p=0.04), and blood glucose (SMD -0.31 [-0.58, -0.05], p=0.02). Therefore, PRT, HIIT and COMB can improve cardiometabolic health in older adults with cardiometabolic risk. Further research is warranted, particularly in HIIT and COMB, to identify the optimal exercise prescription, if any, for improving older adults cardiometabolic health.

DOI: https://doi.org/10.1055/a-1560-6183