Whey protein supplementation with vibration exercise ameliorates lumbar paraspinal muscle atrophy in prolonged bed rest

Optimizing countermeasures for musculoskeletal deterioration during spaceflight is a priority for space agencies. We examined the impact of adding whey protein supplementation to resistive vibration exercise (RVE) on lumbar deconditioning during prolonged bed rest. Participants (n = 12) were enrolled in a crossover design study of 21 days of bed rest with RVE (2 days/wk, 2-4 min/session time under tension), whey protein supplementation plus RVE (NeX), and no-intervention control (CNT). After bed rest, NeX [-2.2 (7.0)%, P = 0.370], but not RVE [-5.6 (6.4)%, P = 0.0027], reduced paraspinal muscle atrophy compared with CNT [-6.1 (5.5)%, P = 0.00035]. After 3 days of bed rest, whole intervertebral disk (IVD) T2 increased in all groups [CNT: +5.3 (2.5)%, P < 0.0001; NeX: +6.3 (1.8)%, P < 0.0001; RVE: +6.3 (1.9)%, P < 0.0001] and remained at this level on day 21 of bed rest [CNT: 5.5 (2.6)%, P < 0.0001; NeX: 6.0 (1.8)%, P < 0.0001; RVE: 6.2 (2.8)%, P < 0.0001]. Increases in IVD T2 were greatest in the nucleus [10.9 (1.1)%, P < 0.0001], with reductions of T2 observed in the anterior annulus [-4.4 (1.0) %, P = 0.00001] and increases in the posterior annulus [2.1 (0.8)%, P = 0.011]. At 6 and 28 days post-bed rest, IVD T2 was similar compared with baseline for all groups. A similar pattern was seen for IVD height, although a -3.8 (4.6)% (P = 0.0052) reduction of IVD height was seen 28 days after bed rest in the CNT group. The countermeasures did not impact on the presence or intensity of back pain during or after bed rest. Participants reporting back pain on day 3 of bed rest had greater (P = 0.013) increases in intervertebral disk volume than participants who did not. Although neither countermeasure impacted IVD changes or back pain in prolonged bed rest, NeX, but not RVE alone, ameliorated paraspinal muscle atrophy.NEW & NOTEWORTHY We examined the impact of adding protein supplementation to exercise (resistive vibration exercise) as a countermeasure against changes in the spine during spaceflight simulation. We found that adding the protein supplementation reduced spine muscle atrophy more than exercise alone. Neither countermeasure approach prevented changes in the disks in the spine or impacted back pain reports