A cross-sectional study of physical activity and arterial compliance: the effects of age and artery size.

Our study examined the relationship between habitual high levels of vigorous physical activity on large and small artery compliance via radial artery pulse wave analysis. Eighty-three healthy men (n = 44) and women (n = 39), aged 18-78 years, were recruited as habitually less active (light-to-moderate exercise ≤3 times/wk) or habitually highly active (vigorous exercise ≥5 times/wk). A multivariate analysis of variance revealed a significant interaction of age and activity level; habitual vigorous activity was associated with greater compliance in large and small arteries in older adults (40-78 years) and younger adults (18-22 years). In the large and small arteries, we observed an age-associated decrease in arterial compliance (aged ≥ 40 years), though it appears to be less pronounced in the large artery among habitually highly active subjects. This study suggests that aging may be associated with declines in large and small artery compliance that can be attenuated by habitual vigorous activity.

A Ketogenic Diet in Rodents Elicits Improved Mitochondrial Adaptations in Response to Resistance Exercise Training Compared to an Isocaloric Western Diet.

Purpose: Ketogenic diets (KD) can facilitate weight loss, but their effects on skeletal muscle remain equivocal. In this experiment we investigated the effects of two diets on skeletal muscle mitochondrial coupling, mitochondrial complex activity, markers of oxidative stress, and gene expression in sedentary and resistance exercised rats. Methods: Male Sprague-Dawley rats (9-10 weeks of age, 300-325 g) were fed isocaloric amounts of either a KD (17 g/day, 5.2 kcal/g, 20.2% protein, 10.3% CHO, 69.5% fat, n = 16) or a Western diet (WD) (20 g/day, 4.5 kcal/g, 15.2% protein, 42.7% CHO, 42.0% fat, n = 16) for 6 weeks. During these 6 weeks animals were either sedentary (SED, n = 8 per diet group) or voluntarily exercised using resistance-loaded running wheels (EXE, n = 8 per diet group). Gastrocnemius was excised and used for mitochondrial isolation and biochemical analyses. Results: In the presence of a complex II substrate, the respiratory control ratio (RCR) of isolated gastrocnemius mitochondria was higher (p < 0.05) in animals fed the KD compared to animals fed the WD. Complex I and IV enzyme activity was higher (p < 0.05) in EXE animals regardless of diet. SOD2 protein levels and GLUT4 and PGC1α mRNA expression were higher (p < 0.05) in EXE animals regardless of diet. Conclusion: Our data indicate that skeletal muscle mitochondrial coupling of complex II substrates is more efficient in chronically resistance trained rodents fed a KD. These findings may provide merit for further investigation, perhaps on humans.

Post-exercise branched chain amino acid supplementation does not affect recovery markers following three consecutive high intensity resistance training bouts compared to carbohydrate supplementation.

BACKGROUND: Amino acid supplementation has been shown to potentially reduced exercise-induced muscle soreness. Thus, the purpose of this study was to examine if branched chain amino acid and carbohydrate (BCAACHO) versus carbohydrate-only sports drink (CHO) supplementation attenuated markers of muscle damage while preserving performance markers following 3 days of intense weight training. METHODS: Healthy resistance-trained males (n = 30) performed preliminary testing (T1) whereby they: 1) donated a baseline blood draw, 2) performed knee extensor dynamometry to obtain peak quadriceps isometric and isokinetic torque as well as electromyography (EMG) activity at 60°/s and 120°/s, and 3) performed a one repetition maximum (1RM) barbell back squat. The following week participants performed 10 sets x 5 repetitions at 80 % of their 1RM barbell back squat for 3 consecutive days and 48 h following the third lifting bout participants returned for (T2) testing whereby they repeated the T1 battery. Immediately following and 24 h after the three lifting bouts, participants were randomly assigned to consume one of two commercial products in 600 mL of tap water: 1) BCAAs and CHO (3 g/d L-leucine, 1 g/d L-isoleucine and 2 g/d L-valine with 2 g of CHO; n = 15), or 2) 42 g of CHO only (n = 15). Additionally, venous blood was drawn 24 h following the first and second lifting bouts and 48 h following the third bout to assess serum myoglobin concentrations, and a visual analog scale was utilized prior, during, and after the 3-d protocol to measure subjective perceptions of muscular soreness. RESULTS: There were similar decrements in 1RM squat strength and isokinetic peak torque measures in the BCAA-CHO and CHO groups. Serum myoglobin concentrations (p = 0.027) and perceived muscle soreness (p < 0.001) increased over the intervention regardless of supplementation. A group*time interaction was observed for monocyte percentages (p = 0.01) whereby BCAA-CHO supplementation attenuated increases in this variable over the duration of the protocol compared to CHO supplementation. CONCLUSION: BCAA-CHO supplementation did not reduce decrements in lower body strength or improve select markers of muscle damage/soreness compared to CHO supplementation over three consecutive days of intense lower-body training.

Testosterone inhibits expression of lipogenic genes in visceral fat by an estrogen-dependent mechanism.

The influence of the aromatase enzyme on the chronic fat-sparing effects of testosterone requires further elucidation. Our purpose was to determine whether chronic anastrozole (AN, an aromatase inhibitor) treatment alters testosterone-mediated lipolytic/lipogenic gene expression in visceral fat. Ten-month-old Fischer 344 rats (n = 6/group) were subjected to sham surgery (SHAM), orchiectomy (ORX), ORX + treatment with testosterone enanthate (TEST, 7.0 mg/wk), or ORX + TEST + AN (0.5 mg/day), with drug treatment beginning 14 days postsurgery. At day 42, ORX animals exhibited nearly undetectable serum testosterone and 29% higher retroperitoneal fat mass than SHAM animals (P < 0.001). TEST produced a ∼380-415% higher serum testosterone than SHAM (P < 0.001) and completely prevented ORX-induced visceral fat gain (P < 0.001). Retroperitoneal fat was 21% and 16% lower in ORX + TEST than SHAM (P < 0.001) and ORX + TEST + AN (P = 0.007) animals, while serum estradiol (E2) was 62% (P = 0.024) and 87% (P = 0.010) higher, respectively. ORX stimulated lipogenic-related gene expression in visceral fat, demonstrated by ∼84-154% higher sterol regulatory element-binding protein-1 (SREBP-1, P = 0.023), fatty acid synthase (P = 0.01), and LPL (P < 0.001) mRNA than SHAM animals, effects that were completely prevented in ORX + TEST animals (P < 0.01 vs. ORX for all). Fatty acid synthase (P = 0.061, trend) and LPL (P = 0.043) mRNA levels were lower in ORX + TEST + AN than ORX animals and not different from SHAM animals but remained higher than in ORX + TEST animals (P < 0.05). In contrast, the ORX-induced elevation in SREBP-1 mRNA was not prevented by TEST + AN, with SREBP-1 expression remaining ∼117-171% higher than in SHAM and ORX + TEST animals (P < 0.01). Across groups, visceral fat mass and lipogenic-related gene expression were negatively associated with serum testosterone, but not E2 Aromatase inhibition constrains testosterone-induced visceral fat loss and the downregulation of key lipogenic genes at the mRNA level, indicating that E2 influences the visceral fat-sparing effects of testosterone.

A putative low-carbohydrate ketogenic diet elicits mild nutritional ketosis but does not impair the acute or chronic hypertrophic responses to resistance exercise in rodents.

We examined whether acute and/or chronic skeletal muscle anabolism is impaired with a low-carbohydrate diet formulated to elicit ketosis (LCKD) vs. a mixed macronutrient Western diet (WD). Male Sprague-Dawley rats (9-10 wk of age, 300-325 g) were provided isoenergetic amounts of a LCKD or a WD for 6 wk. In AIM 1, basal serum and gastrocnemius assessments were performed. In AIM 2, rats were resistance exercised for one bout and were euthanized 90-270 min following exercise for gastrocnemius analyses. In AIM 3, rats voluntarily exercised daily with resistance-loaded running wheels, and hind limb muscles were analyzed for hypertrophy markers at the end of the 6-wk protocol. In AIM 1, basal levels of gastrocnemius phosphorylated (p)-rps6, p-4EBP1, and p-AMPKα were similar between diets, although serum insulin (P < 0.01), serum glucose (P < 0.001), and several essential amino acid levels (P < 0.05) were lower in LCKD-fed rats. In AIM 2, LCKD- and WD-fed rats exhibited increased postexercise muscle protein synthesis levels (P < 0.0125), but no diet effect was observed (P = 0.59). In AIM 3, chronically exercise-trained LCKD- and WD-fed rats presented similar increases in relative hind limb muscle masses compared with their sedentary counterparts (12-24%, P < 0.05), but there was no between-diet effects. Importantly, the LCKD induced "mild" nutritional ketosis, as the LCKD-fed rats in AIM 2 exhibited ∼1.5-fold greater serum ß-hydroxybutyrate levels relative to WD-fed rats (diet effect P = 0.003). This study demonstrates that the tested LCKD in rodents, while only eliciting mild nutritional ketosis, does not impair the acute or chronic skeletal muscle hypertrophic responses to resistance exercise.

Influence of endurance exercise training on antioxidant enzymes, tight junction proteins, and inflammatory markers in the rat ileum.

BACKGROUND: This study investigated the effects of endurance exercise training on ileum antioxidant status, as well as tight junction, inflammatory, and nutrient transporter gene expression. METHODS: Sprague-Dawley rats (4 month old) were assigned to sedentary (SED) or endurance exercise-training (EXE) groups (n = 8/group). EXE animals were trained on the treadmill for 10 days at a speed of 30 m/min at 0° incline for 60 min/day. SED and EXE animals were sacrificed (24 h after the final training bout) and the ileum was stored for analyses. RESULTS: The ileum of EXE had higher (p < 0.05) antioxidant protein levels of manganese superoxide dismutase and catalase compared to SED with no change (p > 0.05) in the lipid peroxidation biomarker 4-hydroxynonenal. Ileum mRNA expression of the tight junction gene zonulin increased (p < 0.05) and claudin 1 decreased (p < 0.05) in EXE compared to SED, but occludin and zonula occluden 1 were not different (p > 0.05) between SED and EXE. The ileum mRNA expressions of seven nutrient transporters (SLC5A8, SLC7A6, SLC6A19, SLC7A7, SLC27A2, SLC16A10, and SLC15A1) were not different between the two groups (p > 0.05). EXE had lower ileum TNFα mRNA expression (p < 0.05) compared to SED. No changes (p > 0.05) were found in the other inflammatory mRNAs including NFκB, IFNγ, IL6, CCL2, TLR4, and IL10. In addition, no changes in p-p65:p65 were detected. CONCLUSIONS: These findings suggest that 10 days of endurance exercise training up-regulates key endogenous antioxidant enzymes, decreases select inflammation markers, and alters select markers of tight junction permeability.