Moreover, Baier et al. [37] examined the effects of a 2–3 g of a daily ingestion of HMB-Ca in combination with amino acids for one year in the elderly and found that HMB consumption did not result in any changes in blood or urine markers of hepatic or renal function or blood lipids. Although the previous studies found no adverse events associated with HMB supplementation, a recent rodent study found an increase in plasma insulin after 320 mg·kg·BM-1/·d-1 supplementation

for one month, which showed a significant increase in fasting insulin levels, suggesting a possible PARP inhibitor decrease in insulin sensitivity [38]. However, this finding has not been reported in any previous human study. Evidence to date indicates that that consumption of HMB is safe in both young and old populations; however, future studies CUDC-907 mw examining the effects of HMB on insulin sensitivity in humans are warranted. The effects of HMB supplementation on skeletal muscle damage, protein breakdown, and recovery HMB is presently thought to work by speeding regenerative capacity of skeletal muscle following high intensity or prolonged exercise [7]. Researchers have used a number of dependent measures to examine this attribute including serum indices of skeletal muscle damage (GDC-0068 nmr creatine kinase [CK], and lactate dehydrogenase [LDH]), and urinary indicators of protein breakdown (3-methyl-histidine

[3-MH] and urea nitrogen) [10, 11, 17]. Perceived

recovery and skeletal muscle soreness have also Nintedanib (BIBF 1120) been investigated following training with, and without HMB supplementation [39]. Of the studies reviewed which investigated skeletal muscle damage and recovery (Table 1), there were a variety of supplement protocols (1 day to 6 weeks; pre vs. post exercise), age ranges (19–50 yrs), training protocols (progressive resistance vs. isokinetic dynamometer), and subject-training statuses (untrained, moderately to highly resistance trained, and endurance trained). Some studies included other supplements, such as creatine monohydrate, while others consisted of HMB alone. Diet and training were controlled in some studies, but not in others (Table 1). For these reasons, results across studies have not been consistent. Effects of training status Training status has been a variable that has received a great deal of interest in the literature. When training and/or diet are controlled, a number of studies have demonstrated that HMB can lower indices of skeletal muscle damage and protein breakdown in a dose dependent fashion in untrained populations [7, 10, 20]. For example, Nissen et al. [7] found that HMB blunted the rise in indicators of skeletal muscle damage and protein degradation, CK, LDH, blood and urinary urea nitrogen, and 3-MH (20-60%) after three weeks of high intensity, monitored resistance exercise.