Downhill Running Excessive Training Inhibits Hypertrophy in Mice Skeletal Muscles with Different Fiber Type Composition

Abstract

The aim of this study was to verify the effects of running overtraining protocols performed in downhill, uphill, and without inclination on the proteins related to hypertrophy signaling pathway in extensor digitorum longus (EDL) and soleus of C57BL/6 mice. We also performed histological and stereological analyses. Rodents were divided into control (CT; sedentary mice), overtrained by downhill running (OTR/down), overtrained by uphill running (OTR/up), and overtrained by running without inclination (OTR). The incremental load, exhaustive, and grip force tests were used as performance evaluation parameters. 36 h after the grip force test, EDL and soleus were removed and immediately used for immunoblotting analysis or stored at -80°C for histological and stereological analyses. For EDL, OTR/down decreased the protein kinase B (Akt) and tuberous sclerosis protein 2 (TSC2) phosphorylation (p), and increased myostatin, receptor-activated Smads (pSMAD2-3), and insulin receptor substrate-1 (pIRS-1; Ser307/636). OTR/down also presented low and high relative proportions of cytoplasm and connective tissue, respectively. OTR/up increased the mammalian target of rapamycin (pmTOR), 70-kDa ribosomal protein S6 kinase 1 (pS6K1) and pSMAD2-3, and decreased pTSC2. OTR decreased pTSC2 and increased pIRS-1 (Ser636). For soleus, OTR/down increased S6 ribosomal protein (pS6RP) and pSMAD2-3, and decreased pIRS-1 (Ser639). OTR/up decreased pS6K1, pS6RP and pIRS-1 (Ser639), and increased pTSC2 (Ser939), and pSMAD2-3. OTR increased pS6RP, 4E-binding protein-1 (p4E-BP1), pTSC2 (Ser939), and pSMAD2-3, and decreased pIRS-1 (Ser639). In summary, OTR/down inhibited the skeletal muscle hypertrophy with concomitant signs of atrophy in EDL. The effects of OTR/up and OTR depended on the analyzed skeletal muscle type.

Excessive treadmill training enhances the insulin signaling pathway and glycogen deposition in mice hearts

“…The results of these performance evaluations for the TR, OTR/down, OTR/up, and OTR groups have been previously described in detail by our research group . Additionally, the blood lactate levels of these experimental groups have been previously described …”

Hypothalamic endoplasmic reticulum stress of overtrained mice after recovery

“…The animals were maintained in individual cages with controlled temperature (22±2°C) on a 12:12-h inverted light-dark cycle (light: 6 pm to 6 am, dark: 6 am to 6 pm), with water and food (Purina chow) available ad libitum. The experimental procedures were approved by the Ethics Committee of USP (ID 14.1.873.53.0) and the experimental groups were manipulated and/or overtrained in a dark room between 6 to 8 am 13,[18][19][20][21][22] .…”

“…Each week of the downhill, uphill and without inclination OT running protocols consisted of 5 days of training, followed by 2 days of recovery, and were applied as previously described 13,[18][19][20][21][22] . The performance evaluations were done at week 0 and 48 h after the last sessions of the OT protocols at the end of week 10 and consisted of a rotarod test 13,22,24 , the ILT 13,[18][19][20][21][22] , an exhaustive test 13,18-22 and a grip force test 13,[18][19][20][21][22]25 .…”

“…The performance evaluations were done at week 0 and 48 h after the last sessions of the OT protocols at the end of week 10 and consisted of a rotarod test 13,22,24 , the ILT 13,[18][19][20][21][22] , an exhaustive test 13,18-22 and a grip force test 13,[18][19][20][21][22]25 . The description of these tests and their results were made available recently 13 , using the same sample as this study.…”

Nonfunctional overreaching and hepatic adaptations of APPL1 and APPL2

“…The resting interval between daily sessions during the eighth week was 4h. The performance evaluations were made on week 0 and 48 h after the last sessions of the OT protocols at the end of week 8 and consisted of a rotarod test 12,14,15 , the ILT 3,12,14,[16][17][18] , an exhaustive test 3,12,14,[16][17][18] and a grip force test 3,12,14,[16][17][18] . The description of these tests and their results were recently published 3 using the same sample as the current study.…”