BACKGROUND: Bodybuilding is an established competitive sport with the goal of presenting a balanced physique while emphasizing muscular size and leanness. Little is known about the effects of the off-season training phase, often called the “bulking phase,” on important health-related outcomes (e.g., aerobic fitness [VO2 max] and cardiometabolic risk [CMR] factors). The purpose of this study was to compare VO2 max, body composition, and CMR factors in natural male bodybuilders (BB) in the off-season training phase with those of recreationally active young males (RA). METHODS: Participants completed one laboratory visit in which body composition was determined via DEXA (General Electric), as well as BIA using an InBody 770 analyzer. Thereafter, 40 microliters of blood were collected and analyzed for plasma CMR factors (fasting total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, and glucose) using an Alere Cholestech LDX analyzer. Participants then performed a treadmill GXT to volitional exhaustion, and expired gases were measured using a Parvomedics TrueOne 2400 to determine VO2 max. RESULTS: A total of 8 BB (age = 21.8 2.9 yrs, body mass = 89.3 ± 13.0 kg) and 7 RA (24.6 ± 2.1 yrs, body mass = 81.5 ± 10.5 kg) completed the study. Compared with RA, BB exhibited a leaner body fat percentage (12.9 ± 4.7 vs 21.0 ± 4.2% fat, p = 0.004) and less fat mass (11.4 ± 4.2 vs 17.0 ± 3.7 kg, p = 0.018), though body mass did not differ significantly (p = 0.23). Although VO2 max was not significantly different, RA tended to exhibit higher VO2 max (60.5 ± 5.5 vs 54.5 ± 7.6 mlO2·kg of fat-free mass-1·min-1, p = 0.108), only when VO2 max was expressed relative to fat-free mass (mlO2·kg of fat-free mass-1·min-1). Likewise, there were no differences between groups in CMR factors, but BB tended to exhibit lower HDL cholesterol (40.2 ± 11.1 vs 53.6 ± 13.5 mg·dl-1, p = 0.100) and higher total cholesterol: HDL cholesterol ratio (4.1 ± 1.7 vs 2.8 ± 0.65, p = 0.088). CONCLUSIONS: Although BB exhibited similar absolute VO2 max as RA, their VO2 max relative to fat-free mass (mlO2·kg of fat-free mass-1·min-1) tended to be lower, and their CMR profiles tended to be less favorable. These findings may be explained in part by the absence of aerobic exercise performed by BB in the off-season training phase, and highlights the importance of BB considering CMR, particularly during the bulking phase of training.

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