Intramuscular adipose tissue, muscle area, and power as predictors of performance in breast cancer survivors.

PURPOSE: The decline in physical performance, assessed by physical tests such as the timed up and go (TUG) test, is a consequence of reduced physiological reserves at higher levels of a hierarchical process. This occurs due to changes in muscle architecture, including atrophy and fat infiltration into the muscles, which in turn lead to changes in muscle function, resulting in reduced muscle strength and power and, consequently, affecting physical performance. This study investigated predictive factors for physical performance in breast cancer survivor (BCS), focusing on intramuscular adipose tissue (IMAT), quadríceps muscle area (QMA), and muscular power. METHODS: This observational, analytical, and cross-sectional study included 23 women without a history of cancer (age, 58.5 ± 8.3 years; BMI, 27.2 ± 5.1 kg/m2) and 56 BCS (age, 58.5 ± 8.3 years; BMI, 27.2 ± 5.1 kg/m2). QMA and IMAT were assessed using computed tomography images. Muscular power and physical performance were measured using the 5-repetition sit-to-stand and TUG tests, respectively. RESULTS: IMAT (r = 0.4, P < 0.01) and muscular power (r = - 0.4, P < 0.01) were associated with TUG performance in BCS, whereas QMA (r = - 0.22, P = 0.10) showed no significant association. QMA (r = 0.55, P < 0.01) was associated with muscular power, while no significant association was found between IMAT and muscular power (r = - 0.05, P = 0.73). Age explained 19% (P < 0.01) of TUG performance variability. Adding muscular power increased explanatory power by 12% (P < 0.01), and including IMAT further increased it by 7% (P = 0.02) for TUG performance. Collectively, age, muscular power, and IMAT accounted for 38% of the performance variance in the TUG test (age, B = 0.06, P = 0.043; muscular power, B = - 0.01, P = 0.002; IMAT, B = - 0.05, P = 0.020). CONCLUSIONS: Our findings suggest that IMAT and muscular power predict the physical performance of BCS, while QMA does not have the same predictive capability.

The relationship between depressive symptoms and physical performance in postmenopausal women: a cross-sectional investigation.

OBJECTIVE: The relationship between depressive symptoms and declining physical performance in postmenopausal women has been extensively examined. However, various confounding factors can influence this association. This study aimed to investigate the link between depressive symptoms and physical performance in postmenopausal women while considering potential interfering factors. METHODS: In this cross-sectional study, 137 postmenopausal women were categorized into two groups based on the presence of depressive symptoms (n = 58; mean ± SD age, 60.12 ± 8.45 y) and absence of depressive symptoms (n = 79; mean ± SD age, 60.72 ± 7.45) using the Geriatric Depression Scale (short version) (GDS-15). Thoracic kyphosis angle was measured using the flexicurve method. Physical performance was assessed through various tests, including Timed Up and Go, Five Times Stand and Sit Test, 6-minute Walking Speed, 10-meter Usual Walking Speed, 10-meter Fast Walking Speed, and dynamometry. The study compared variables between the two groups and used linear regression models adjusted for dynamometry, kyphosis angle, age, antidepressant usage, sitting time, and fall history to evaluate the relationship between GDS-15 scores and physical performance. RESULTS: Significant differences were observed in physical performance, body mass index, kyphosis angle, antidepressant usage, sitting time, and fall history between women with and without depressive symptoms. The GDS-15 showed a negative association with all walking speed tests (10-meter Usual Walking Speed, m/s; P < 0.001; B = -0.01; 10-meter Fast Walking Speed, m/s; P < 0.001; B = -0.02; 6-minute Walking Speed, m/s; P < 0.004; B = -0.01) and a positive association with the Five Times Stand and Sit Test ( P < 0.002; B = 0.21) and Timed Up and Go ( P < 0.001; B = 0.13) tests, regardless of grip strength, kyphosis angle, age, antidepressant use, sitting time, or fall history in postmenopausal women. CONCLUSIONS: This study underscores the independent and substantial impact of depressive symptoms on the physical performance of postmenopausal women. These findings emphasize the importance of addressing both mental health and physical well-being when providing care and support for this demographic.

Ischemic Preconditioning Improves the Bench-Press Maximal Strength in Resistance-Trained Men.

We investigated whether acute ischemic preconditioning (IPC) would affect upper limb maximal strength performance in resistance-trained men. Using a counterbalanced randomized crossover design, fifteen men (29.9 ± 5.9 yrs.; 86.3 ± 9.6 kg; 8.0 ± 5.0 yrs. resistance training experience) performed one-repetition maximum (1-RM) bench press tests on three different occasions: control, 10 min post-IPC or 10 min post-placebo (SHAM). One-way analysis of variance showed that the post-IPC condition increased (P < 0.0001) 1-RM loads compared to both control and post-SHAM (control 113.3 ± 15.9 kg vs. SHAM 113.9 ± 15.8 kg vs. IPC 115.7 ± 15.6 kg), while control and SHAM did not differ (P > 0.05). Individual results showed that 13 participants (~87%) improved their performance post-IPC compared to control, and 11 participants (~73%) performed better post-IPC compared to post-SHAM. Reported session rating of perceived exertion (RPE) was lower (P < 0.0001) post-IPC (8.5 ± 0.6 arb.u) compared to control (9.3 ± 0.5 arb.u) and post-SHAM (9.3 ± 0.5 arb.u). Therefore, we conclude that IPC acutely improves upper limb maximal strength performance and reduces session-RPE in resistance-trained men. These results suggest an acute ergogenic effect of IPC for strength and power sports such as powerlifting.

The Impact of ACTN3 Gene Polymorphisms on Susceptibility to Exercise-Induced Muscle Damage and Changes in Running Economy Following Downhill Running.

This study aimed to investigate if ACTN3 gene polymorphism impacts the susceptibility to exercise-induced muscle damage (EIMD) and changes in running economy (RE) following downhill running. Thirty-five healthy men were allocated to the two groups based on their ACTN3 gene variants: RR and X allele carriers. Neuromuscular function [knee extensor isometric peak torque (IPT), rate of torque development (RTD), and countermovement, and squat jump height], indirect markers of EIMD [muscle soreness, mid-thigh circumference, knee joint range of motion, and serum creatine kinase (CK) activity], and RE (oxygen uptake, minute ventilation, blood lactate concentration, and perceived exertion) for 5-min of running at a speed equivalent to 80% of individual maximal oxygen uptake speed were assessed before, immediately after, and 1-4 days after a 30-min downhill run (-15%). Neuromuscular function was compromised (P < 0.05) following downhill running with no differences between the groups, except for IPT, which was more affected in the RR individuals compared with the X allele carriers immediately (-24.9 ± 6.9% vs. -16.3 ± 6.5%, respectively) and 4 days (-16.6 ± 14.9% vs. -4.2 ± 9.5%, respectively) post-downhill running. EIMD manifested similarly for both the groups except for serum CK activity, which was greater for RR (398 ± 120 and 452 ± 126 U L-1 at 2 and 4 days following downhill running, respectively) compared with the X allele carriers (273 ± 121 and 352 ± 114 U L-1 at the same time points). RE was compromised following downhill running (16.7 ± 8.3% and 11 ± 7.5% increases in oxygen uptake immediately following downhill running for the RR and X allele carriers, respectively) with no difference between the groups. We conclude that although RR individuals appear to be more susceptible to EIMD following downhill running, this does not extend to the changes in RE.

A single bout of downhill running attenuates subsequent level running-induced fatigue.

Fatigue can be defined as exercise-induced strength loss. During running, fatigue can be partially explained by repetitive low-intensity eccentric contractions-induced muscle damage (EIMD). Previous studies showed that a bout of downhill running (DR) attenuated subsequent EIMD. Thus, we tested if a 30-min DR bout would attenuate fatigue induced by subsequent 60-min level running (LR). Twenty-seven male college students were randomly allocated to an experimental (EXP) or a control (CON) group. All participants performed LR on a treadmill at 70% of the velocity (vVO2peak) corresponding to peak oxygen uptake (VO2peak). Only EXP performed a 30-min DR (- 15%) on a treadmill at 70% vVO2peak fourteen days before LR. Indirect EIMD markers and neuromuscular function were assessed before, immediately and 48 h after DR and LR. Knee extension isometric peak torque (IPT) decreased (- 36.3 ± 26%, p < 0.05) immediately following DR with full recovery reached 48 h post-DR. Muscle soreness developed (p < 0.05) immediately (37 ± 25 mm) and 48 h (45 ± 26 mm) post-DR. IPT and rate of torque development (RTD) at late phases (> 150 ms) from the onset of muscle contraction decreased significantly (- 10.7 ± 6.1% and from - 15.4 to - 18.7%, respectively) immediately after LR for the CON group and remained below baseline values (- 5.6 ± 8.5% and from - 13.8 to - 14.9%, respectively) 48 h post-LR. However, IPT and late RTD were not significantly affected by LR for the EXP group, showing a group x time interaction effect. We concluded that a single DR bout can be used to attenuate fatigue induced by a LR performed fourteen days after.

Does rest interval between sets affect resistance training volume, density, and rating of perceived exertion when adopting the crescent pyramid system in young women?

BACKGROUND: The rest interval between sets can affect the responses to resistance training. Thus, the purpose of this study was to compare the effects of different rest intervals (RI) on volume, density, and rating of perceived exertion (RPE) when adopting a crescent pyramid (CP) system. METHODS: Twenty young women (21.1±2.6 years, 1.59±0.06 m, 58.5±9.3 kg) participated in this study. All participants performed three experimental sessions of the leg press exercise in 5 sets until voluntary muscular failure at 60%, 65%, 70%, 75%, and 80% of one-repetition maximum (1RM). A randomized and crossover design was used so that in each session one of three RI (RI-1 = 1 min, RI-2 = 2 min, and RI-3 = 3 min) was tested. RESULTS: The participants performed a significantly larger volume in the RI-3 (12820±3134 kg) when compared to RI-1 (10367±3053 kg) condition (P<0.05). The volume did not differ between RI-2 and RI-3 (P>0.05). The density was higher (P<0.05) in RI-1 (43.1±12.7 kg/s) when compared RI-2 (25.6±5.8 kg/s) and RI-3 (17.7±4.3 kg/s). The RI-2 presented higher density compared to RI-3 condition (P<0.05). The RPE was not different between the three conditions (P>0.05). CONCLUSIONS: The use of 2 minutes of rest between sets allowed the performance of a high volume-load and density of the session in young women. In addition, the three experimental sessions provided a high perception of effort.

Novel renal biomarkers show that creatine supplementation is safe: a double-blind, placebo-controlled randomized clinical trial.

The aim of this study was to evaluate the impact of creatine supplementation (CS) on renal function in young, healthy, and active subjects. We used a randomized, double-blind, placebo-controlled clinical trial as the study design. Thirty-six healthy male university students were recruited and divided into three groups: group placebo, group G3 (3 g/day of CS), and group G5 (5 g/day of CS). To assess renal function, new kidney biomarkers, kidney injury molecule-1 (KIM-1) and monocyte chemoattractant protein-1 (MCP-1), were quantified. Serum albumin, serum creatinine, serum urea, estimated glomerular filtration rate (eGFR), proteinuria, and albuminuria were also measured. All groups were evaluated at two times: prior CS or placebo (pre) and after 35 days on CS or placebo (post). After 35 days of intervention, all characteristics were maintained without significant difference (P > 0.05) between the groups, including serum creatinine, eGFR, and more sensitive kidney biomarker concentrations (KIM-1 and MCP-1). The paired analysis showed that the supplemented groups (G3 and 5G) had increased serum creatinine and decreased eGFR levels (P < 0.05). However, the values were still within the normal reference range. In conclusion, the results of renal function evaluation did not show any difference between the evaluated groups. Increased serum creatinine and decreased eGFR levels in CS groups can be explained by increased creatine stores and metabolism, since creatinine is a by-product of creatine metabolism. These findings indicate that the use of CS at doses of 3 g and 5 g/day for a short period (35 days) is safe and did not impair the kidneys or renal function in young healthy subjects.

Impact of Moderate Aerobic Training on Physical Capacities of Hypertensive Obese Elderly.

The association of old age and chronic conditions, such as hypertension and obesity, can lead to larger decreases in the physical capacities of elderly, compared with their healthy counterparts. Physical exercise has been demonstrated to be efficient in postponing this phenomenon, mainly strength training. However, little is known about the effect of aerobic training on this condition. The aim of this work was to investigate the impact of 12 weeks of moderate-intensity aerobic training on the physical capacities of hypertensive obese older women. Aerobic power, lower limb muscle power, upper limb muscle strength, endurance, and flexibility of 19 hypertensive obese elders were evaluated. Afterward, patients were blindly randomized into control group (CG) and exercise group (EG). EG underwent three sessions/week of 60 min of moderate-intensity aerobic training, during 12 weeks. EG showed increases in VO2max compared with CG (p = .03) and increases in flexibility compared with basal moment (+21.6%; p = .01) after 12 weeks, whereas CG did not show any significant alterations. Moderate aerobic training is capable of inducing increases in maximal aerobic power and flexibility in hypertensive obese elderly. However, other essential physical capacities associated with independence in elderly people (i.e., muscle power and strength) were not responsive to this kind of protocol.

Resistance training associated with the administration of anabolic-androgenic steroids improves insulin sensitivity in ovariectomized rats.

The aim of the present study was to investigate the effects of anabolic-androgenic steroids and resistance training (RT) on insulin sensitivity in ovariectomized rats. Adult female Wistar rats were divided into ten experimental groups (n = 5 animals per group): (1) sedentary (Sed-Intact); (2) sedentary ovariectomized (Sed-Ovx); (3) sedentary nandrolone (Sed-Intact-ND); (4) sedentary ovariectomized plus nandrolone (Sed-Ovx-ND); (5) trained (TR-Intact); (6) trained nandrolone (TR-Intact-ND); (7) trained ovariectomized (TR-Ovx); (8) trained ovariectomized plus nandrolone; (9) trained sham; and (10) trained ovariectomized plus sham. Four sessions of RT were used, during which the animals climbed a 1.1 m vertical ladder with weights attached to their tails. The sessions were performed once every 3 days, with between four and nine climbs and with eight to twelve dynamic movements per climb. To test the sensitivity of insulin in the pancreas, glucose and insulin tolerance tests were performed. For insulin sensitivity, there was a statistically significant interaction for the TR-Ovx group, which presented higher sensitivity than the Sed-Intact, Sed-Ovx, and TR-Intact groups. Sed-Intact-ND and TR-Intact-ND groups exhibited higher values of insulin sensitivity than the Sed-Intact group. Except for the TR-Intact group, sensitivity was greater in trained groups than in the Sed-Intact group. There was higher insulin sensitivity in the TR-Intact-ND group than in the Sed-Intact and Sed-Intact-ND groups (P < 0.05). In conclusion, ovariectomy and short-term RT alone induced no change on insulin action. Administration of nandrolone decanoate improved insulin action, mainly when it was associated with RT.