Biology subjects

Agyin-Birikorang, A.

Publications and source records attributed to Agyin-Birikorang, A..

3 recordsLinked to original sources

bioRxiv2023

The effects of resistance training on denervated myofibers, senescent cells, and associated protein markers in middle-aged adults

Denervated myofibers and senescent cells are hallmarks of skeletal muscle aging. However, sparse research has examined how resistance training affects these outcomes. We investigated the effects of unilateral leg extensor resistance training on denervated myofibers, senescent cells, and associated protein markers in middle-aged participants (MA, 55{+/-}8 years old, 17 females, 9 males). We obtained vastus lateralis (VL) muscle cross-sectional area (mCSA), VL biopsies, and strength assessments before and after training. Fiber cross-sectional area (fCSA), satellite cells (Pax7+), denervated myofibers (NCAM+), senescent cells (p16+ or p21+), senescence-related proteins, and senescence-associated secretory phenotype (SASP) proteins were analyzed from biopsied muscle. Leg extensor peak torque increased after training (p<0.001), while VL mCSA trended upward (p=0.082). No significant changes were observed for fCSA, NCAM+ myofibers, or senescent (p16+ or p21+) cells, albeit satellite cells increased after training (p=0.037). While >90% satellite cells were not p16+ or p21+, most p16+ and p21+ cells were Pax7+ (>90% on average). Training altered 13/46 proteins related to muscle-nerve communication (all upregulated, p<0.05) and 10/19 proteins related to cellular senescence (9 upregulated, p<0.05). Only 1/17 SASP proteins increased with training (IGFBP-3, p=0.031). In conclusion, resistance training upregulates proteins associated with muscle-nerve communication in MA participants but does not alter NCAM+ myofibers. Moreover, while training increases senescence-related proteins in skeletal muscle, this coincided with an increase in satellite cells but not alterations in senescent cell content or SASP proteins. Hence, we interpret these collective findings as resistance training being an unlikely inducer of cellular senescence in humans.

physiology↗

bioRxiv2023

Hip thrust and back squat training elicit similar gluteus muscle hypertrophy and transfer similarly to the deadlift

PurposeWe examined how set-volume equated resistance training using either the back squat (SQ) or hip thrust (HT) affected hypertrophy and various strength outcomes. MethodsUntrained college-aged participants were randomized into HT or SQ groups. Surface electromyograms (sEMG) from the right gluteus maximus and medius muscles were obtained during the first training session. Participants completed nine weeks of supervised training (15-17 sessions), before and after which we assessed muscle cross-sectional area (mCSA) via magnetic resonance imaging and strength via three-repetition maximum (3RM) testing and an isometric wall push test. ResultsGlutei mCSA growth was similar across both groups. Estimates [(-) favors HT; (+) favors SQ] modestly favored the HT compared to SQ for lower [effect {+/-} SE, -1.6 {+/-} 2.1 cm2], mid [-0.5 {+/-} 1.7 cm2], and upper [-0.5 {+/-} 2.6 cm2], but with appreciable variance. Gluteus medius+minimus [-1.8 {+/-} 1.5 cm2] and hamstrings [0.1 {+/-} 0.6 cm2] mCSA demonstrated little to no growth with small differences between groups. Thigh mCSA changes were greater in SQ for the quadriceps [3.6 {+/-} 1.5 cm2] and adductors [2.5 {+/-} 0.7 cm2]. Squat 3RM increases favored SQ [14 {+/-} 2.5 kg] and hip thrust 3RM favored HT [-26 {+/-} 5 kg]. 3RM deadlift [0 {+/-} 2 kg] and wall push strength [-7 {+/-} 13 N] similarly improved. All measured gluteal sites showed greater mean sEMG amplitudes during the first bout hip thrust versus squat set, but this did not consistently predict gluteal hypertrophy outcomes. ConclusionNine weeks of squat versus hip thrust training elicited similar gluteal hypertrophy, greater thigh hypertrophy in SQ, strength increases that favored exercise allocation, and similar strength transfers to the deadlift and wall push.

physiology↗

bioRxiv2023

A novel deep proteomic approach in human skeletal muscle unveils distinct molecular signatures affected by aging and resistance training

We examined the myofibrillar (MyoF) and non-myofibrillar (non-MyoF) proteomic profiles of the vastus lateralis (VL) muscle of younger (Y, 22{+/-}2 years old; n=5) and middle-aged participants (MA, 56{+/-}8 years old; n=6), and MA following eight weeks of knee extensor resistance training (RT, 2d/week). Shotgun/bottom-up proteomics in skeletal muscle typically yields wide protein abundance ranges that mask lowly expressed proteins. Thus, we adopted a novel approach whereby the MyoF and non-MyoF fractions were separately subjected to protein corona nanoparticle complex formation prior to digestion and Liquid Chromatography Mass Spectrometry (LC-MS) analysis. A total of 10,866 proteins (4,421 MyoF and 6,445 non-MyoF) were identified. Across all participants, the number of non-MyoF proteins detected averaged to be 5,645{+/-}266 (range: 4,888-5,987) and the number of MyoF proteins detected averaged to be 2,611{+/-}326 (range: 1,944-3,101). Differences in the non-MyoF (8.4%) and MyoF (2.5%) proteome were evident between age cohorts. Further, most of these age-related non-MyoF proteins (447/543) were more enriched in MA versus Y. Several biological processes in the non-MyoF fraction were predicted to be operative in MA versus Y including (but not limited to) increased cellular stress, mRNA splicing, translation elongation, and ubiquitin-mediated proteolysis. Non-MyoF proteins associated with splicing and proteostasis were further interrogated, and in agreement with bioinformatics, alternative protein variants, spliceosome-associated proteins (snRNPs), and proteolysis-related targets were more abundant in MA versus Y. RT in MA non-significantly increased VL muscle cross-sectional area (+6.5%, p=0.066) and significantly increased knee extensor strength (+8.7%, p=0.048). However, RT modestly altered the MyoF ([~]0.3%, 11 upregulated and two downregulated proteins) and non-MyoF proteomes ([~]1.0%, 56 upregulated and eight downregulated proteins, p<0.01). Further, RT did not affect predicted biological processes in either fraction. Although participant numbers were limited, these preliminary results using a novel deep proteomic approach in skeletal muscle suggest that aging and RT predominantly affects protein abundances in the non-contractile protein pool. However, the marginal proteome adaptations occurring with RT suggest either: a) this may be an aging-associated phenomenon, b) more rigorous RT may stimulate more robust effects, or c) RT, regardless of age, subtly affects skeletal muscle protein abundances in the basal state.

physiology↗