Eccentric and Concentric Resistance Exercise Comparison for Knee Osteoarthritis Introduction This study aimed to compare the efficacy of eccentrically focused resistance exercise (ECC RT) to concentrically focused resistance exercise (CNC RT) on knee osteoarthritis (OA) symptoms and strength. Methods Ninety participants consented. Participants were randomized to CNC RT, ECC RT, or a wait-list, no-exercise control group. Four months of supervised exercise training was completed using traditional weight machines (CNC RT) or modified-matched machines that overloaded the eccentric action (ECC RT). Main outcomes included one-repetition maximal strength (knee extension, leg flexion, and leg press), weekly rate of strength gain, Western Ontario and McMaster University Osteoarthritis Index (WOMAC) total score and subscores. Results Fifty-four participants (60–85 yr, 61% women) completed the study. Both CNC RT and ECC RT groups showed 16%–28% improvement relative to the wait-list, no-exercise control group (P = 0.003–0.005) for all leg strength measures. The rate of weekly strength gain was greater for CNC RT than for ECC RT for leg press and knee flexion (by 2.9%–4.8%; both, P < 0.05) but not knee extension (0.7%; P = 0.38). There were no significant differences in WOMAC total and subscores across groups over time. Leg press strength change was the greatest contributor to change in WOMAC total scores (R2 = 0.223). The change in knee flexion strength from baseline to month 4 was a significant predictor of the change in WOMAC pain subscore (F ratio = 4.84, df = 45, P = 0.032). Both modes of strength training were well tolerated. Conclusions Both resistance training types effectively increased leg strength. Knee flexion and knee extension muscle strength can modify function and pain symptoms irrespective of muscle contraction type. Which mode to pick could be determined by preference, goals, tolerance to the contraction type, and equipment availability.

Myocardial Adaptations to Competitive Swim Training Purpose Swim training is performed in the prone or supine position and obligates water immersion, factors that may augment cardiac volume loading more than other endurance sports. At present, prospective data defining the cardiac responses to swim training are lacking. We therefore studied myocardial adaptations among competitive swimmers to establish a causal relationship between swim training and left ventricular (LV) remodeling. Methods Collegiate swimmers were studied before and after a 90-d period of training intensification. Transthoracic echocardiography was used to examine LV structural and functional adaptations under resting conditions and during an acute LV afterload challenge generated by isometric handgrip testing (IHGT). A sedentary control population was identically studied with IHGT. Results In response to a discrete period of swim training intensification, athletes (n = 17, 47% female, 19 ± 0.4 yr old) experienced eccentric LV remodeling, characterized by proportionally more chamber dilation than wall thickening, with attendant enhancements of resting LV systolic (LV twist) and diastolic (early and late phase tissue velocities) function. Compared with baseline and controls, athletes posttraining demonstrated greater systolic twist impairment during IHGT. However, training-induced LV dilation coupled with gains in diastolic function offsets this acquired systolic susceptibility to acute afterload, resulting in the relative preservation of stroke volume during IHGT. Conclusion Swim training, a sport characterized by unique cardiac loading conditions, stimulates eccentric LV remodeling with the concomitant augmentation of systolic twist and diastolic relaxation. This volume-mediated cardiac remodeling appears to result in greater systolic susceptibility to acute afterload challenge. Further work is required to establish how training-induced changes in function translate to human performance and whether these are accompanied by physiologic trade-offs with relevance to common forms of heart disease.

Association between Lifelong Physical Activity and Disease Characteristics in HCM Purpose Hypertrophic cardiomyopathy (HCM) is characterized by inappropriate left ventricular (LV) wall thickness. Adaptations to exercise can occasionally mimic certain HCM characteristics. However, it is unclear whether physical activity affects HCM genotype expression and disease characteristics. Consequently, we compared lifelong physical activity volumes between HCM gene carriers with and without HCM phenotype, and compared disease characteristics among tertiles of physical activity in phenotypic HCM patients. Methods We enrolled n = 22 genotype positive/phenotype negative (G+/P−) HCM gene carriers, n = 44 genotype positive/phenotype positive (G+/P+) HCM patients, and n = 36 genotype negative/phenotype positive (G−/P+) HCM patients. Lifelong physical activity was recorded using a questionnaire and quantified as metabolic equivalent of task hours per week. Results We included 102 participants (51 ± 16 yr, 49% male). Lifelong physical activity volumes were not different between G+/P+ and G+/P− subjects (16 [10–29] vs 14 [6–26] metabolic equivalent of task‐hours per week, P = 0.33). Among phenotypic HCM patients, there was no difference in LV wall thickness, mass, and late gadolinium enhancement across physical activity tertiles. Patients with the highest reported physical activity volumes were younger at the time of diagnosis (tertile 1: 52 ± 14 yr, tertile 2: 49 ± 15 yr, tertile 3: 41 ± 18 yr; P = 0.03), and more often had a history of nonsustained ventricular tachycardia (4% vs 30% vs 30%, P = 0.03). Conclusions Lifelong physical activity volumes are not associated with genotype-to-phenotype transition in HCM gene carriers. We also found no difference in LV wall thickness across physical activity tertiles. However, the most active HCM patients were younger at the time of diagnosis and had a higher arrhythmic burden. These observations warrant further exploration of the role of exercise in HCM disease development.

Resistance Exercise Counteracts Tumor Growth in Two Carcinoma Rodent Models Purpose Although resistance exercise (RE) is now recognized as an adjuvant in cancer treatment because of its capacity to prevent muscle wasting, weakness, and cachexia, it is unknown whether RE can mitigate tumor development. Two solid adenocarcinoma models (Walker-256 and Ehrlich) were used to investigate the effects of RE on tumor cell proliferation, growth, and aggressiveness parameters in tumor-bearing animals’ life span. Methods Walker-256 tumor-bearing rats and Ehrlich tumor-bearing mice were subjected to RE, which consisted of climbing a ladder apparatus with loads tied to their tails. After 4 wk, animals were euthanized, and tumors were excised and assessed for tumor microenvironment evaluation such as cell proliferation and apoptosis determination, collagen deposit, and presence of malignant tumor morphology. Results Our data demonstrate that RE mitigated tumor growth and favored tumor end points such as lower Scarff–Bloom–Richardson histological grade tumor, denoting slow cell aberrant form and division, decreased tumor cell proliferation (evaluated by nucleus marked with antigen ki-67), and lower viable tumor area in both types of tumors studied. In addition, RE stimulated tumor microvessel density in Walker-256 tumor-bearing rats, but there was no change in their life span. Conclusion RE may mitigate tumor growth and tumor malignancy parameters such as lower histopathological grade, assuming less nuclear pleomorphism and mitotic cells, smaller viable tumor area, and decreased tumor cell proliferation in both adenocarcinomas. In addition, RE induced tumor vascularization.

Endurance Exercise Prevents Metabolic Distress–induced Senescence in the Hippocampus Purpose Metabolic disorder such as obesity and type 2 diabetes caused by excess caloric intake is associated with an increased risk of neurodegenerative diseases. Endurance exercise (EXE) has been suggested to exert neuroprotective effects against the metabolic distress. However, the exact underlying molecular mechanisms responsible for the exercise-induced neuroprotection have not been fully elucidated. In this study, we investigated whether EXE-induced neuroprotection is associated with cellular senescence, neuroinflammation, and oxidative stress using a mouse model of obesity induced by a high-fat/high-fructose diet. Methods C57BL/6 female mice (10 wk old) were randomly divided to three groups: normal chow diet group (CON, n = 11), high-fat diet/high-fructose (HFD/HF) group (n = 11), and high-fat diet/high-fructose + endurance exercise (HFD/HF + EXE) group (n = 11). HFD/HF + EXE mice performed treadmill running exercise for 60 min·d−1, 5 d·wk−1 for 12 wk. Results Our data showed that EXE ameliorated HFD/HF-induced weight gain, fasting blood glucose levels, and visceral fat gain. More importantly, HFD/HF diet promoted cellular senescence, whereas EXE reversed it, evidenced by a reduction in the levels of p53, p21, p16, beta-galactosidase (SA-β-gal), and lipofuscin. Furthermore, EXE prevented HFD/HF-induced neuroinflammation (e.g., tumor necrosis factor-α and interleukin-1β) by inhibiting toll-like receptor 2 downstream signaling cascades (e.g., tumor necrosis factor receptor–associated factor 6, c-Jun N-terminal kinase, and c-Jun) in parallel with reduced reactive glial cells. This anti-inflammatory effect of EXE was associated with the reversion of HFD/HF-induced cellular oxidative stress. Conclusion Our study provides novel evidence that EXE-induced antisenescence against metabolic distress in the hippocampus may be a key neuroprotective mechanism, preventing neuroinflammation and oxidative stress.

Low Stroke Volume during Exercise with Hot Skin Is Due to Elevated Heart Rate It is well known that hyperthermia lowers stroke volume (SV) during moderate-intensity prolonged exercise, yet the underlying mechanism is inconclusive, especially when skin temperature (Tsk) is hot (≥38°C). Purpose In the present study, HR was independently lowered by a low dose of β1-blockade (βB) to investigate its effect on SV during exercise when skin is hot. The effect of rapid skin cooling on reversing cardiovascular responses was also examined. Methods Nine men cycled at 62% V˙O2peak wearing a water-perfused suit for 20 min during three conditions: (a) moderate Tsk (~33°C) (MOD), (b) hot Tsk (~38°C) (HOT), and (c) hot Tsk (38°C) with βB (HOT-βB). Skin temperature was then rapidly cooled at 20 min in all trials by cold water (0°C–2°C) perfusion while subjects continued cycling for another 20 min. Results When HR was lowered during HOT-βB (152 ± 4 bpm) to the same level as MOD (150 ± 4 bpm; P = 0.30), SV in HOT-βB (132 ± 8 mL) was also restored to the same level as MOD (129 ± 7 mL, P = 0.37) even with a significantly higher cutaneous blood flow (CBF) and lower mean arterial blood pressure. When Tsk was rapidly cooled, cardiac output, HR, and CBF significantly decreased while SV remained lower in HOT. Forearm venous volume was not different between trials during heating and cooling. Conclusions The increase in HR rather than an increase in CBF or forearm venous volume was responsible for the decrease in SV during moderate-intensity exercise when Tsk was held at 38°C.

Change in Physical Activity and Cardiac Structure over 10 Years: The Multi-Ethnic Study of Atherosclerosis Introduction Physical activity (PA) is inversely associated with risk of heart failure and cardiovascular disease (CVD), whereas increased left ventricular (LV) mass and mass to volume (m:v) ratio are unfavorable CVD risk factors. We assessed whether changes in leisure time PA were associated with longitudinal changes in cardiac structure in a community-based population. Methods We included 2779 Multi-Ethnic Study of Atherosclerosis participants, free of baseline CVD, who had available data on PA and cardiac magnetic resonance imaging at examinations 1 (2000–2002) and 5 (2010–2012). Physical activity was measured by a Typical Week PA Survey and converted to MET-minutes per week of moderate+vigorous activity. We used linear mixed effect models to estimate the associations of baseline and change in PA with baseline and change in cardiac structure, adjusting for CVD risk factors and body size. Results At baseline, the mean age was 59 yr, 53% were women, and 58% of nonwhite race/ethnicity. During average 10-yr follow-up, and after accounting for baseline PA levels, the highest quintiles of PA increase were significantly associated with increases in LV mass (2.3 g; 95% confidence interval [CI], 0.4–4.2), LV end-diastolic volume (4.7 mL; 95% CI, 2.4–7.0), and stroke volume (3.3 mL; 95% CI, 1.6–5.1), but lower M:V ratio (−2.9; 95% CI, −5.0 to −0.8) compared with the lowest quintiles. Increasing exercise PA was associated with increases in LV diameter and reductions in M:V ratio, whereas occupational PA was associated with increases in m:v ratio. Increasing PA over 10 yr was also associated with greater risk of eccentric dilated LV hypertrophy at examination 5. Conclusions After accounting for baseline PA, greater positive changes in leisure-time PA levels were associated with a more eccentric-type of LV remodeling pattern over 10 yr. The clinical implications of such findings remain to be determined.

Protein Supplementation Does Not Augment Adaptations to Endurance Exercise Training Introduction Recently, it has been speculated that protein supplementation may further augment the adaptations to chronic endurance exercise training. We assessed the effect of protein supplementation during chronic endurance exercise training on whole-body oxidative capacity (V˙O2max) and endurance exercise performance. Methods In this double-blind, randomized, parallel placebo-controlled trial, 60 recreationally active males (age, 27 ± 6 yr; body mass index, 23.8 ± 2.6 kg·m−2; V˙O2max, 47 ± 6 mL·min−1·kg−1) were subjected to 12 wk of triweekly endurance exercise training. After each session and each night before sleep, participants ingested either a protein supplement (PRO; 28.7 g casein protein) or an isoenergetic carbohydrate placebo (PLA). Before and after the 12 wk of training, V˙O2max and endurance exercise performance (~10-km time trial) were assessed on a cycle ergometer. Muscular endurance (total workload achieved during 30 reciprocal isokinetic contractions) was assessed by isokinetic dynamometry and body composition by dual-energy x-ray absorptiometry. Mixed-model ANOVA was applied to assess whether training adaptations differed between groups. Results Endurance exercise training induced an 11% ± 6% increase in V˙O2max (time effect, P < 0.0001), with no differences between groups (PRO, 48 ± 6 to 53 ± 7 mL·min−1·kg−1; PLA, 46 ± 5 to 51 ± 6 mL·min−1·kg−1; time–treatment interaction, P = 0.50). Time to complete the time trial was reduced by 14% ± 7% (time effect, P < 0.0001), with no differences between groups (time–treatment interaction, P = 0.15). Muscular endurance increased by 6% ± 7% (time effect, P < 0.0001), with no differences between groups (time–treatment interaction, P = 0.84). Leg lean mass showed an increase after training (P < 0.0001), which tended to be greater in PRO compared with PLA (0.5 ± 0.7 vs 0.2 ± 0.6 kg, respectively; time–treatment interaction, P = 0.073). Conclusion Protein supplementation after exercise and before sleep does not further augment the gains in whole-body oxidative capacity and endurance exercise performance after chronic endurance exercise training in recreationally active, healthy young males.

The Longitudinal Associations of Fitness and Motor Skills with Academic Achievement Purpose This study aimed to examine both independent and dependent longitudinal associations of physical fitness (PF) components with academic achievement. Methods A total of 954 fourth to seventh graders (9–15 yr [Mage = 12.5 yr], 52% girls) from nine schools throughout Finland participated in a 2-yr follow-up study. Register-based academic achievement scores (grade point average [GPA]) and PF were assessed in the spring of 2013–2015. Aerobic fitness was measured with a maximal 20-m shuttle run test, muscular fitness with curl-up and push-up tests, and motor skills with a 5-leaps test and a throwing–catching combination test. Structural equation modeling was applied to examine the longitudinal associations adjusting for age, gender, pubertal stage, body fat percentage, learning difficulties, and mother’s education. Results The changes in aerobic and muscular fitness were positively associated with the changes in GPA (B = 0.27, 99% confidence interval [CI] = 0.06–0.48; B = 0.36, 99% CI = 0.11–0.63, respectively), whereas the changes in motor skills were not associated with the changes in GPA. Better motor skills in year 2 predicted better GPA a year later (B = 0.06, 99% CI = 0.00–0.11; B = 0.06, 99% CI = 0.01–0.11), whereas aerobic and muscular fitness did not predict GPA. GPA in year 1 predicted both aerobic (B = 0.08, 99% CI = 0.01–0.15) and muscular (B = 0.08, 99% CI = 0.02–0.15) fitness, and motor skills (B = 0.08, 99% CI = 0.02–0.15) a year later. Conclusion The changes in both aerobic and muscular fitness were positively associated with the changes in academic achievement during adolescence, whereas the changes in motor skills had only borderline significant association. However, better motor skills, although not systematically, independently predicted better academic achievement 1 yr later, whereas aerobic or muscular fitness did not. Better academic achievement predicted better motor skills, aerobic fitness, and muscular fitness. Developmental changes in adolescence may induce parallel and simultaneous changes in academic achievement and PF.

Examining Arm Vascular Function and Blood Flow Regulation in Row-trained Males Vascular function and blood flow responses to upper limb exercise are differentially altered in response to different exercise training modalities. Rowing is a unique exercise modality that incorporates the upper limbs and can significantly augment upper limb endurance, strength, and power capacity. Purpose This study sought to determine whether vascular function and blood flow regulation during handgrip exercise are altered in row-trained males. Methods Nine young row-trained males (ROW, 20 ± 1 yr; V˙O2peak = 51 ± 2 mL·kg−1·min−1) and 14 recreationally active male controls (C: 22 ± 1 yr; V˙O2peak = 37 ± 2 mL·kg−1·min−1) were recruited for this study. Subjects performed multiple bouts of progressive rhythmic handgrip exercise. Brachial artery (BA) diameter, blood flow, shear rate, and mean arterial pressure were measured at rest and during the last minute of each exercise workload. Results Resting values for BA diameter, blood flow, shear rate, and mean arterial pressure were not different between groups. During handgrip exercise, the ROW group reported significantly lower BA blood flow (ROW vs C: 4 kg [146 ± 21 vs 243 ± 13 mL·min−1], 8 kg [248 ± 29 vs 375 ± 17 mL·min−1], 12 kg [352 ± 43 vs 490 ± 22 mL·min−1]) across all workloads when compared with controls. The examination of BA dilation, when controlled for the shear rate stimulus and evaluated across all workloads, was revealed to be significantly greater in ROW group versus controls. Conclusion This study revealed that vascular function and blood flow regulation were significantly different in row-trained males when compared with untrained controls evidenced by greater shear-induced BA dilation and lower arm blood flow during progressive handgrip exercise.