Medicine and Science in Sports and Exercise最新文献

Purpose: Obesity increases colon cancer risk that has been previously linked to marrow-derived myeloid cells. We previously demonstrated that exercise training (EX) prevents colon cancer initiation, potentially through reduced myelopoiesis. However, it remains unknown whether early myeloid cell accumulation and inflammation in the colon precedes carcinogenesis with high-fat diet (HFD)-induced obesity, and if EX can attenuate these effects. We hypothesized that obesity would promote colon carcinogenesis that was preceded by myeloid cell accumulation and inflammation that would be attenuated by EX.

Methods: C57BL/6 mice were randomized to a HFD or control (CON) diet for 8 weeks. The HFD mice switched to CON diet and all mice were given intraperitoneal injections of azoxymethane (AOM) to induce colon cancer and randomized into EX or sedentary (SED) conditions.

Results: HFD mice developed more aberrant crypt foci (ACF), a marker for early carcinogenesis, compared with CON ( P < 0.01), and EX developed fewer ACF compared with SED ( P < 0.0001). Marrow-derived ( P < 0.001) CD206 + macrophages were elevated in HFD compared with CON at study week 16 ( P < 0.01). Marrow-derived CD206 - macrophages ( P < 0.05) and marrow-derived ( P < 0.05) CD206 + macrophages were more abundant in HFD compared with CON at study week 42. EX did not alter colon immune cell populations. β-catenin protein was higher in HFD compared with CON at study week 42 ( P < 0.05), and STAT3 protein content was lower at study week 28 with EX compared with SED ( P < 0.05).

Conclusions: The results suggest that obesity promotes colon ACF formation, potentially through early inflammatory myeloid cell accumulation. Despite attenuating ACF, EX did not alter myeloid cell accumulation in the colon, suggesting that EX inhibits ACF formation through alternative mechanisms which may include reduced β-catenin and STAT3 signaling.

Purpose: To open up new horizons of translational research, we studied the lactate threshold (LT)-dependent physiological responses and adaptations to exercise in rats, highlighting the importance of intensity-specific studies for optimizing exercise prescriptions. LT is physiologically related to the noninvasive gas exchange threshold (GET), and both thresholds are moderate-heavy-intensity boundary indices in determining an effective intensity of aerobic training in humans. Although their practical utility is presumed to extend to rats, the actual existence of GET, the thresholds' relations to maximal oxygen consumption (V̇O 2max ), and whether aerobic adaptations by training differ around the LT intensity remain uncertain.

Methods: This study sought to identify the GET using our previously established rat LT model by combining the use of a metabolic chamber and the V-slope method, and to confirm the thresholds' relations to V̇O 2max . We investigated changes in the thresholds and V̇O 2max following 6 wk of endurance training at below or above LT intensity.

Results: GET and LT were significantly correlated and agreed with high precision, although with a fixed bias. Untrained rats exhibited GET and LT at 56% and 52% of their V̇O 2max , respectively. Endurance training at supra-, but not below-, the LT intensity significantly improved V̇O 2max and both thresholds; however, their %V̇O 2max remained unaltered.

Conclusions: GET in rats is identifiable as a threshold associated with LT using the V-slope method. Furthermore, both thresholds can serve as moderate-heavy-intensity boundary indices for the aerobic training of rats. This study advances our understanding of exercise intensity regulation in rats, thereby contributing to the development of a more nuanced and effective model for exercise prescription, with implications for human health and fitness.

Purpose: With aging, the decline in preferred walking speed (PWS), influenced by the increased energy cost of walking (CoW), is a key predictor of morbidity. However, the determinants associated with PWS and CoW remain poorly understood, especially after 80 yr old. The aim of the study was to characterize the amplitude and mechanisms of age-related decline in CoW and PWS in old (OM) and very old (VOM) men.

Methods: Thirty-nine young men (YM; 22.1 ± 3.4 yr), 34 OM (71.7 ± 4.1 yr), and 23 VOM (85.8 ± 2.7 yr) performed aerobic, neuromuscular, and gait assessments. Net CoW was measured on a treadmill. Physical activity (PA) was evaluated by questionnaire and accelerometry.

Results: Net CoW was 32% ( P < 0.001), 19% ( P < 0.01), and 26% ( P < 0.001) higher in VOM compared with OM for 1.11 m·s -1 , 1.67 m·s -1 , and PWS. Net CoW was also 27% ( P < 0.001), 26% ( P < 0.01), and 29% ( P < 0.001) higher in OM compared with YM at these speeds. Linear regression stratified by age showed that net CoW at PWS was associated with step frequency ( r = 0.79; P < 0.001) for OM and with both coefficient of variation of stride mean time ( r = 0.48; P < 0.05) and maximal strength of knee extensors ( r = -0.54; P < 0.05) for VOM. The same analysis revealed that PWS was correlated with net CoW ( r = -0.56; P < 0.05) and PA ( r = 0.47; P < 0.05) in VOM.

Conclusions: The progressive increase in net CoW with age was associated with gait and neuromuscular impairments, particularly after the age of 80 yr. This increase in net CoW was related to a decrease in PWS in VOM, suggesting an adaptation of PWS to compensate for the increase in energy demand. Maintaining a high level of PA may potentially delay the age-related decline in PWS despite an age-related increase in net CoW.

Objective: This study aimed to identify potential changes in cardiorespiratory fitness among athletes who had previously been infected with severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2).

Methods: In this prospective observational multicenter hybrid study (CoSmo-S), cardiopulmonary exercise testing on treadmills or bicycle ergometers involving 2314 athletes (39.6% female) was conducted. German federal squad members (59.6%) and non-squad athletes were included in the study. A total of 1170 (37.2% female) subjects were tested positive for SARS-CoV-2 via polymerase chain reaction from which we had pre-SARS-CoV-2 infection examinations available for 289 subjects. Mixed-effect models were employed to analyze, among others, the following dependent variables: power output at individual anaerobic threshold (PO IAT ·kg -1 ), maximal power output (PO max ·kg -1 ), measured V̇O 2max ·kg -1 , heart rate at individual anaerobic threshold (HR IAT ), and maximal heart rate (HR max ).

Results: A SARS-CoV-2 infection was associated with a decrease in PO IAT ·kg -1 (-0.123 W·kg -1 , P < 0.001), PO max ·kg -1 (-0.099 W·kg -1 , P = 0.002), and measured V̇O 2max ·kg -1 (-1.70 mL·min -1 ·kg -1 , P = 0.050), and an increase in HR IAT (2.50 bpm, P = 0.008) and HR max (2.59 bpm, P < 0.001) within the first 60 d after SARS-CoV-2 infection. Using the pandemic onset in Germany as a longitudinal reference point, the healthy control group showed no change over time in these variables and an increase in PO max (+0.126 W·kg -1 , P = 0.039) during the first 60 d after the reference point. Subgroup analyses showed that both squad members and endurance athletes experienced greater decreases in cardiorespiratory fitness compared with non-squad members respectively athletes from explosive power sports.

Conclusions: A SARS-CoV-2 infection is associated with a decline in cardiorespiratory fitness in athletes for approximately 60 d. Potential factors contributing to this outcome seem to be cardiopulmonary and vascular alterations in consequence of SARS-CoV-2. A minor effect on cardiorespiratory fitness has training interruption due to acute symptoms and/or quarantine.

Purpose: Cardiorespiratory fitness (CRF) declines with age, and greater declines increase the risk for adverse health outcomes. Understanding factors that attenuate age-related decreases in CRF can help extend healthy life. We sought to determine the longitudinal associations of aerobic physical activity, muscle-strengthening activity (MSA), and adiposity with CRF.

Methods: Study participants were enrolled in the Cooper Center Longitudinal Study and had three or more preventive medical examinations at the Cooper Clinic (Dallas, Texas) during 1987-2019. Aerobic activity and MSA were self-reported, and three measures of adiposity were clinically assessed: body mass index (BMI), body fat percentage, and waist circumference. CRF, expressed as metabolic equivalents (METs), was estimated by a maximal treadmill test. The longitudinal associations of aerobic activity, MSA, and adiposity with CRF were estimated using multivariable mixed linear regression models.

Results: The study included 6105 participants who were followed for a median of 7.1 yr. Most participants were men (83.6%), and their average age at baseline was 47.0 (SD = 8.7) yr. Mean CRF at baseline was 12.2 (SD = 2.3) METs. Increasing aerobic activity (per 500 MET·min·wk -1 , β = 0.069, 95% confidence interval = 0.064-0.074 METs) or MSA (per days per week, β = 0.066, 95% confidence interval = 0.058-0.073 METs) was associated with increased CRF over time. Increasing BMI, body fat percentage, or waist circumference were each associated with decreased CRF over time.

Conclusions: These data offer longitudinal evidence on how changes in aerobic activity, MSA, and various measures of adiposity (beyond BMI) independently correlate with CRF over time. Healthy lifestyle behaviors that include increasing aerobic and MSA and limiting adiposity may positively influence the retention of fitness with age and improve downstream health outcomes.

Purpose: The effect of exercise on serum concentration of vitamin D metabolites remains inconclusive, with studies reporting deviating results. This study evaluated the acute effect of a single session of two specific exercise forms; strength training (ST) and high-intensity interval training (HIIT), on circulating 25-hydroxyvitamin D (25(OH)D), free25(OH)D and 1,25-dihydroxyvitamin D (1,25(OH)2D), and skeletal muscle vitamin D receptor (VDR) gene expression, in healthy adults.

Methods: Thirty-nine participants (19 women and 20 men, age 21-30 years) completed a single bout of ST and HIIT exercise, separated by two weeks. Serum concentration of total 25(OH)D, free25(OH)D and 1,25(OH)2D were assessed before exercise, immediately after, and 3 hours and 24 hours after each session. Muscle biopsies were obtained at rest (1st visit), and at 3 hours and 24 hours post ST and HIIT, and analyzed for VDR gene expression. Repeated measures ANOVA was used to assess serum concentration across time, while paired samples t-test was used for muscle VDR gene expression analyses.

Results: Serum concentration of 25(OH)D or free 25(OH)D did not change after either exercise mode when correcting for plasma volume alterations. 1,25(OH)2D was reduced by 13.1 ± 18.3 pmol/L and 7.1 ± 9.6 pmol/L immediately after ST and HIIT, respectively (P < 0.001). Muscle VDR mRNA expression increased after ST by 3.1 ± 1.8 (3 hr) and 2.2 ± 1.7 (24 hr) fold change (P < 0.05).

Conclusions: One single session of ST or HIIT did not alter serum concentration of 25(OH)D and free 25(OH)D when correcting for plasma volume changes. Both exercise modes caused a transient reduction in 1,25(OH)2D suggesting utilization of 1,25(OH)2D by muscle cells following exercise. Elevated VDR gene expression following ST suggests a functional role of VDR in fast-twitch muscle fibers.

Purpose: To examine the physiological, power-duration, nutritional intake and training characteristics of the recent lightweight (- 75 kg) 50+, 60+ and 70 + yr world champion indoor rowers.

Methods: Laboratory assessments, undertaken over 2 visits, examined body composition, pulmonary function, blood lactate/ventilatory landmarks, efficiency, fat/carbohydrate oxidation, primary component time-constant to steady-state [𝜏pc]) and peak oxygen consumption (V̇O2peak). Training, performance and nutritional intake were also reported.

Results: The athletes' world championship 2000 m times were 06:34.8, 06:44.0 and 07:15.2, respectively. Their training distribution could be considered pyramidal, with ≈65% in the moderate domain, ≈30% in heavy/severe domains and ≈5% in the extreme domain (rowing ≈67 km.week-1). The athletes demonstrated highly-developed attributes such as fat free mass (FFM; [63.4 to 68.1 kg]), forced vital capacity (4.9 to 5.5 L), 𝜏PC; [13.8 to 17.4 s]), peak power output (550 to 797 W), V̇O2peak (56.2 to 44.7 mL.kg.min-1) and critical power (217 to 288 W). Comparisons with young Olympic champion rowers suggest that age-related 2000 m performance mean power declines of -21.6 to -41.4% in world champions ≈25-, 35-, and 45-years older may be predominantly driven by 'central' factors (e.g., V̇O2peak, critical power; -18.1 to -43.8%). In contrast, 'peripheral' factors (e.g., gross efficiency, τPC; +6.1 to -25.1%) seem to display notable preservation despite ageing, aligning closely with values seen in young Olympic champions.

Conclusions: These results challenge conventional perspectives of age-related physiological capacities and decline trajectories. They also suggest that, commensurate with adequate training and nutritional provision, various physiologic systems can exhibit remarkable adaptability and sustain exceptionally high function during ageing. Finally, large differences among the athletes' power-duration and physiological characteristics imply that achieving world-class rowing performance can be predicated by diverse cardiovascular, metabolic and neuromuscular attributes.

Purpose: Red blood cells (RBCs) senescence and blood rheology during ultra-endurance running events appear to be impacted differently depending on the race distance. The physiological mechanisms underlying these differences are poorly understood.

Methods: We investigated the effects of three different ultra-trail running races performed in La Reunion Island (Mascareignes, "the 70 km", 70 km/4,000 m D+; Trail Du Bourbon, "the 100 km", 100 km/6,090 m D+; Diagonale des Fous, "the 170 km", 170 km/10,500 m D+) on RBC oxidative stress, RBC senescence and blood rheology in 66 finishers (18 "70 km", 24 "100 km", 24 "170 km").

Results: We observed a decrease in RBC antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase and catalase) positively related to the race distance, and an increase in RBC H2O2 and isoprostane levels after the three races. However, RBC H2O2 and isoprostane levels were found to be higher after the 70 km compared to the 170 km and the 100 km races. RBC phosphatidylserine externalization increased over baseline value after the 70 km only. Chymotrypsin-like and trypsin-like activities of the RBC proteasome were decreased after all races compared to before. RBC-derived microparticles (RBC-MPs) were increased after the 170 km and the 70 km races. Despite increased RBC senescence markers, RBC deformability increased after the three races. Blood viscosity was differently impacted by the three races with a decrease at low shear rate after the two longest races (the 170 km and the 100 km), and an increase at high shear rate after the shortest one (the 70 km).

Conclusions: Our results confirm that ultra endurance running events differently impact on RBC senescence markers and blood viscosity depending on the race distance, and suggest that RBC oxidative stress could play a key role in the observed alterations.

Purpose: We hypothesized that male and female volunteers would exhibit distinct changes in cardiac morphology, systolic, and diastolic function following endurance (END) and resistance (RES) training.

Methods: Thirty-eight females and 26 males participated in a randomized cross-over design trial in which all participants completed 12-weeks END and RES, separated by a 12-week washout. Echocardiograms assessed morphology (left ventricular mass, LVM), systolic function (ejection fraction, EF, and global longitudinal strain, GLS), diastolic function (mitral valve velocities, E, A; tissue Doppler velocities, e', a'), and left atrial volume.

Results: Males responded to RES by increasing LVM (Δ 9.1 ± 14.3 g, P = 0.005), while E/e' increased (Δ 0.74 ± 1.08, P = 0.004, indicating a decline in diastolic function). There were no significant changes in females following RES. In response to END, LVM increased in both males (Δ 8.8 ± 15.7 g, P = 0.008) and females (Δ 6.5 ± 12.5 g, P = 0.004), with no difference in E/e' (Δ -0.29 ± 0.90) in males but a significant difference in females (Δ -0.39 ± 1.06, P = 0.012, indicating an improvement in diastolic function). Systolic function was not impacted significantly by END or RES in either sex.

Conclusions: Our data suggests that females were less responsive to RES training than males, that RES increased LVM and caused a decline in diastolic function (i.e. an increase in E/e') in males, whereas END improved E/e' (i.e. decreased) in females. These data suggest that sex differences exist in cardiac structural and functional adaptations to different forms of exercise training.

Purpose: This study compared %BFUS to %BF4C in young adult athletes.

Methods: University club sport athletes (86 women, 138 men) from a variety of teams participated. ADP, DXA, and bioimpedance spectroscopy were used to measure body volume, bone mineral content, and total body water, respectively, for the 4C model. Ultrasound measurements were taken at three sites to estimate %BFUS. Comparisons between %BFUS and %BF4C were evaluated with Pearson correlation, paired t-test, linear regression, equivalence testing, and plots of individual errors.

Results: For the combined sample of men and women (N = 224), the two methods were highly correlated (r = 0.93) with a constant error (CE) of 0.8% BF (P < .001) and standard error of estimate (SEE) of 3.0% BF. The 90% confidence intervals of the mean difference (0.47 to 1.17) were well within the ±2% BF limits for equivalence testing, and no bias was evident from the error plot. However, equivalence testing failed to remain inside the ±2% BF range for women, and the prediction errors for women (CE = 1.9% BF, P < .001, SEE = 3.2% BF) were larger than for men (CE = 0.1% BF, P = .597, SEE = 2.8% BF).

Conclusions: Overall, the %BFUS errors were low, suggesting that A-mode ultrasound is a valid field measure of %BF for young adult athletes. Accuracy is better for men than women.