Strength Fitness and Body Weight Status on Markers of Cardiometabolic Health

Christian K. Roberts; Mary M. Lee; Michael Katiraie; Shannon L. Krell; Siddhartha S. Angadi; Michael K. Chronley; Christopher S. Oh; Vicent Ribas; Ryan A. Harris; Andrea L. Hevener; Daniel M. Croymans

Disclosures

Med Sci Sports Exerc. 2015;47(6):1211-1218. 

In This Article

Abstract and Introduction

Abstract

Introduction Recent evidence suggests that resistance training (RT) may reduce metabolic and cardiovascular disease risk. We investigated whether overweight/class I obese individuals by BMI classification with high strength fitness exhibit cardiovascular/metabolic phenotypes similar to those overweight/obese and untrained or those normal-weight with high strength fitness.

Methods A total of 90 young males were categorized into three groups: overweight untrained (OU, n = 30, BMI > 27 kg·m−2), overweight trained (OT, n = 30, BMI > 27 kg·m−2, RT ≥ 4 d·wk−1), and normal-weight trained (NT, n = 30, BMI < 25 kg·m−2, RT ≥ 4 d·wk−1). Participants were assessed for strength, body composition, central/peripheral blood pressures, arterial stiffness, and markers of cardiovascular and metabolic health.

Results Body weight was similar in OT and OU and greater than NT (P < 0.00001), and fat mass was different in all groups (P < 0.001). Compared to OU, NT and OT groups exhibited higher relative strength (NT = 46.7%, OT = 44.4%, P < 0.00001), subendocardial viability ratio (NT = 21.0%, P < 0.001; OT = 17.0%, P < 0.01), and lower brachial/central blood pressures (NT P < 0.001; OT P <= 0.05); augmentation index and pulse-wave velocity were lower only in OT (P < 0.05). Total cholesterol, low-density lipoprotein (NT P < 0.01, OT P < 0.05), triglycerides (NT = −50.4%, OT = −41.8%, P < 0.001), oxidized LDL (NT = −39.8%, OT = −31.8%, P < 0.001), and CRP (NT = −63.7%, OT = −67.4%, P < 0.01) levels were lower and high-density lipoprotein (NT = 26.9%, OT = 21.4%, P < 0.001) levels were higher in NT and OT compared to OU. NT and OT also exhibited lower amylin (NT = −55.8%, OT = −40.8%) and leptin (NT = −84.6%, OT = −59.4%) and higher adiponectin (NT = 87.5%, P < 0.001; OT = 78.1%, P < 0.01) and sex hormone–binding globulin (NT = 124.4%, OT = 92.3%, P < 0.001). Despite greater total and trunk fat in OT compared with NT, other than glucose and insulin, which were lower in NT than in both OT and OU (OT P < 0.01, OU P < 0.001), OT did not exhibit any impaired biomarker/phenotype compared to NT.

Conclusions These findings provide evidence that overweight/class I obese individuals with high strength fitness exhibit metabolic/cardiovascular risk profiles similar to normal-weight, fit individuals rather than overweight/class I obese unfit individuals. Strength training may be important to metabolic and cardiovascular health.

Introduction

Obesity is associated with increased risk of type 2 diabetes (T2D), cardiovascular disease (CVD), metabolic syndrome, fatty liver disease and certain forms of cancer, as well as reduced quality of life and increased mortality.[8] At present, more than one-third of U.S. adults remain obese.[21] The causes of obesity are complex, and current intervention programs tend to focus on weight loss as a primary means of ameliorating obesity and its comorbidities.[37] However, numerous lifestyle intervention studies have suggested improvements in indices of cardiovascular and metabolic health independent of weight loss or obesity reversal, which questions the notion that body weight is the cause for increased risk of morbidity and mortality. Weight loss as the primary determinant of successful risk-factor modification is not well supported from either a biological or a behavioral perspective.[33] For example, weight loss–focused interventions face a high rate of recidivism,[3] mediated by a myriad of causes for weight loss variability and weight regain.[32]

Although it is recognized that higher levels of adiposity are correlated with increased mortality, higher levels of fitness attenuate this association. Specifically, cardiorespiratory fit and obese (by body composition) individuals have approximately a 50% lower mortality risk compared to lean and unfit individuals.[17] McAuley et al.[18] noted that among men with high cardiorespiratory fitness, across BMI, waist circumference, and percent body fat categories, there were no significant differences in CVD and all-cause mortality risk, and Lee et al.[17] noted greater improvements in mortality risk with increased fitness compared to changes in body composition. Recent estimates suggest that overweight and class I obese individuals exhibit similar rates of mortality, compared with normal-weight subjects.[8] Thus, the relationship between BMI and mortality is complex and may be influenced by other lifestyle factors, including fitness/training status.

Resistance training (RT) has gained more attention recently for its capacity to increase lean body mass and improve body composition and glucose tolerance.[27] Performing RT and increasing muscular strength has been demonstrated to lower the risk for metabolic syndrome,[13] CVD,[36] and overall mortality.[34] Ortega et al.[23] recently noted that, during a 24-yr follow-up, males 16–19 yr old with initially high levels of hand grip and knee-extension strength had a 20%–35% lower risk of mortality due to CVD, independent of BMI.

Because young individuals are at low risk of mortality, phenotypes associated with disease risk are used as surrogates of health. Thus, the present cross-sectional study was designed to investigate whether overweight/class I obese individuals exhibiting high muscular strength display cardiovascular/metabolic phenotypes similar to overweight/class I obese, untrained individuals or normal-weight individuals with high strength fitness. We recruited 90 young adult men separated into one of three phenotypes characterized by BMI (classified as a categorical variable to compare with existing guidelines) and strength fitness status: normal-weight strength-trained (NT), overweight strength-trained (OT), and overweight untrained (OU). We measured cardiometabolic health phenotypes, including central and brachial blood pressures, indices of arterial stiffness, serum lipids, inflammatory and metabolic markers, and steroid hormones. We hypothesized that: 1) the strength-trained groups, NT and OT, would display better metabolic and cardiovascular phenotypes compared to the OU group; and 2) the strength-trained groups with similar strength fitness levels would exhibit similar metabolic and cardiovascular phenotypes, irrespective of lower body weight and total and trunk fat mass in the NT group.

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