Chronic almond nut snacking alleviates perceived muscle soreness following downhill running but does not improve indices of cardiometabolic health in mildly overweight, middle-aged, adults

Abstract

Introduction: As a popular food snack rich in protein, fiber, unsaturated fatty acids, antioxidants and phytonutrients, almond nut consumption is widely associated with improvements in cardiometabolic health. However, limited data exists regarding the role of almond consumption in improving exercise recovery. Accordingly, we aimed to investigate the impact of chronic almond snacking on muscle damage and cardiometabolic health outcomes during acute eccentric exercise recovery in mildly overweight, middle-aged, adults.

Methods: Using a randomized cross-over design, 25 mildly overweight (BMI: 25.8 ± 3.6 kg/m²), middle-aged (35.1 ± 4.7 y) males (n = 11) and females (n = 14) performed a 30-min downhill treadmill run after 8-weeks of consuming either 57 g/day of whole almonds (ALMOND) or an isocaloric amount (86 g/day) of unsalted pretzels (CONTROL). Muscle soreness (visual analogue scale), muscle function (vertical jump and maximal isokinetic torque) and blood markers of muscle damage (creatine kinase (CK) concentration) and inflammation (c-reactive protein concentration) were measured pre and post (24, 48, and 72 h) exercise. Blood biomarkers of cardiometabolic health (total cholesterol, triglycerides, HDL cholesterol, and LDL cholesterol), body composition and psycho-social assessments of mood (POMS-2 inventory), appetite and well-being were measured pre and post intervention.

Results: Downhill running successfully elicited muscle damage, as evidenced by a significant increase in plasma CK concentration, increased perception of muscle soreness, and impaired vertical jump performance (all p < 0.05) during acute recovery. No effect of trial order was observed for any outcome measurement. However, expressed as AUC over the cumulative 72 h recovery period, muscle soreness measured during a physical task (vertical jump) was reduced by ~24% in ALMOND vs. CONTROL (p < 0.05) and translated to an improved maintenance of vertical jump performance (p < 0.05). However, ALMOND did not ameliorate the CK response to exercise or isokinetic torque during leg extension and leg flexion (p > 0.05). No pre-post intervention changes in assessments of cardiometabolic health, body composition, mood state or appetite were observed in ALMOND or CONTROL (all p > 0.05).

Conclusion: Chronic almond supplementation alleviates task-specific perceived feelings of muscle soreness during acute recovery from muscle damaging exercise, resulting in the better maintenance of muscle functional capacity. These data suggest that almonds represent a functional food snack to improve exercise tolerance in mildly overweight, middle-aged adults.

Keywords: appetite; body composition; exercise tolerance; functional foods; muscle damage.

Figure 1

Overview of study protocol.

Figure 2

Plasma creatine kinase concentration at baseline (pre) and during the 72-h recovery period following downhill running (A) and over the 72 h period expressed as tAUC (B). Data are analysed by two factor repeated measures ANOVA with time and treatment as within-subject factors (A) or by Student’s paired t-test (2 tailed). Data are expressed as means ± SEM.

Figure 3

Plasma c-reactive protein concentration at baseline (pre) and during the 72-h recovery period following downhill running. Data are analyzed by two factor repeated measures ANOVA with time and treatment as within-subject factors. Data are expressed as means ± SEM.

Figure 4

General muscle soreness (0–100 scale) with leg in extension (A,B) and flexion (C,D) positions, or during vertical jump (E,F) and isokinetic dynamometry (G,H) during the 72-h recovery period following downhill running. Data are analyzed by two factor repeated measures ANOVA with time and treatment as within-subject factors (A,C,E,G) or by Student’s paired t-test (2 tailed) (B,D,F,H). Data are expressed as tAUC over the cumulative 72 h recovery period with box and whisker plots. * denotes significant difference from CONTROL (p < 0.05). Data are expressed as means ± SEM.

Figure 5

Peak isokinetic torque during leg extension (A,C) and leg flexion (B,D) at baseline (Pre) and during the 72-h recovery period following downhill running. Measurements conducted at 60°/sec and 90°/sec contraction speeds. Data are analyzed by two factor repeated measures ANOVA with time and treatment as within-subject factors. Data are expressed as means ± SEM.

Figure 6

Vertical jump height during the 72-h recovery period following downhill running. Data are analyzed by two factor repeated measures ANOVA with time and treatment as within-subject factors (A) or by Student’s paired t-test (2 tailed) (B). Data are expressed over time (A) or as tAUC over the cumulative 72 h recovery period with box and whisker plots (B). *Denotes significant difference from CONTROL (p < 0.05). Data are expressed as means ± SEM.