Differences in muscle oxygenation between young and middle-aged recreationally active men during high-volume resistance exercise

The aim of this study was to compare muscle oxygenation of the vastus lateralis during a high-volume isokinetic resistance exercise protocol (HVP) between young adult (YA) and middle-aged adult (MA) men. Twenty recreationally trained men were assigned to either the YA (age 21.8±2.0 years, body mass 90.7±11.6 kg, body height 179±4.7 cm) or MA (age 47.0±4.4 years, body mass 96.1±21.6 kg, body height 177±7.7 cm) group. The HVP consisted of eight sets of 10 repetitions of unilateral isokinetic concentric knee extension and eccentric knee flexion at 60°·s-1. Changes in tissue hemoglobin saturation index (TSI), tissue oxygenated hemoglobin concentration (O2Hb), deoxygenated hemoglobin (HHb), and muscle oxidation index (O2Hb-HHb) were measured during the exercise session using the near-infrared spectroscopy (NIRS). Data were analyzed using two-way mix factorial analyses of variance. Prior to exercise, TSI was significantly greater (p=.024) for YA compared to MA. Significant decreases in O2Hb and O2Hb-HHb and increases in HHb were observed during each of the eight sets relative to the rest periods (p<.05) for both groups. The average change during the eight sets of the HVP revealed a significantly higher (p=.036) level of HHb and a lower (p=.029) level of O2Hb-HHb for MA compared to YA. A significant negative correlation was also noted at baseline between O2Hb-HHb index and the cross-sectional area of the vastus lateralis muscle (r=-.45, p=.045). During a high- volume resistance exercise, MA experienced reduced muscle oxygen saturation levels compared to YA. These results may be attributed to reductions in local tissue oxidative capacity and reduced blood delivery occurring during middle-age, and possibly due to group differences in muscle morphology

Tumor Necrosis Factor-Alpha And Soluble Tnf-Alpha Receptor Responses In Young Vs. Middle-Aged Males Following Eccentric Exercise

Background Tumor necrosis factor-alpha (TNF-α) has been shown to be implicated in both muscle regeneration and muscle wasting. However, it remains unclear whether TNF-α is responsible for the age-related losses in muscle size and function. Also, due to the high clearance rate of TNF-α from circulation, analyzing the circulating levels of soluble TNF-α receptors 1 and 2 (STNFR1 and STNFR2) may provide a better indication of inflammatory events. The aim of this study was to examine changes in circulating concentrations of TNF-α, STNFR1, and STNFR2 following acute eccentric exercise in young (YA) and middle-aged (MA) men. Methods and materials Nine YA (N = 9, 21.8 ± 2.2 y, 179.5 ± 4.9 cm, 91.2 ± 12.2 kg, 21.8 ± 4.3% body fat) and ten MA (N = 10, 47.0 ± 4.4 y, 176.8 ± 7.6 cm; 96.0 ± 21.5 kg, 25.4 ± 5.3% body fat) men completed an acute muscle damaging protocol (MDP). Blood samples were obtained at baseline (BL), immediately (IP), 30-minute (30P), 60-minute (60P), 120-minute (120P), 24-hour (24H), and 48-hour (48H) post-MDP. Lower body performance was assessed via isokinetic dynamometer at BL, IP, 120P, 24H, and 48H. Results YA displayed higher values of peak torque (p = 0.023) and mean torque (p = 0.036) at BL. No significant group differences were observed for markers of muscle damage or TNF-α. Plasma concentrations of TNF-α were unchanged following MDP. STNFR1 concentrations were significantly higher in the YA group compared to MA (p = 0.036). Significant time effects were observed for STNFR1 (p \u3c 0.001) and STNFR2 (p = 0.001). With both groups combined, serum STNFR1 was decreased at 30P (p = 0.001), while STNFR2 was decreased at 30P (p = 0.008), 60P (p = 0.003), and 120P (p = 0.002) relative to BL. Conclusions The pro-inflammatory response to muscle damage does not appear to decline at middle age when individuals are recreationally trained. However, young men showed significantly higher serum STNFR1 concentrations than middle age men. This may suggest that natural inhibitors of TNF-α decline as early as middle age

Comparison Of Two Β-Alanine Dosing Protocols On Muscle Carnosine Elevations

Objective: β-alanine (BA) is a nonproteogenic amino acid that combines with histidine to form carnosine. The amount taken orally in individual doses, however, is limited due to symptoms of paresthesia that are associated with higher doses. The use of a sustained-release formulation has been reported to reduce the symptoms of paresthesia, suggesting that a greater daily dose may be possible. The purpose of the present study was to determine whether increasing the daily dose of BA can result in a similar increase in muscle carnosine in a reduced time. Methods: Eighteen men and twelve women were randomized into either a placebo (PLC), 6-g BA (6G), or 12-g BA (12G) groups. PLC and 6G were supplemented for 4 weeks, while 12G was supplemented for 2 weeks. A resting blood draw and muscle biopsy were obtained prior to (PRE) and following (POST) supplementation. Plasma and muscle metabolites were measured by high-performance liquid chromatography. The loss in peak torque (ΔPT) was calculated from maximal isometric contractions before and after 250 isokinetic kicks at 180°·sec−1 PRE and POST. Results: Both 12G (p = 0.026) and 6G (p = 0.004) increased muscle carnosine compared to PLC. Plasma histidine was decreased from PRE to POST in 12G compared to PLC (p = 0.002) and 6G (p = 0.001), but no group x time interaction (p = 0.662) was observed for muscle histidine. No differences were observed for any hematological measure (e.g., complete blood counts) or in symptoms of paresthesia among the groups. Although no interaction was noted in ΔPT, a trend (p = 0.073) was observed. Conclusion: Results of this investigation indicate that a BA supplementation protocol of 12 g/d−1, using a sustained-release formulation, can accelerate the increase in carnosine content in skeletal muscle while attenuating paresthesia

Influence Of Skeletal Muscle Carnosine Content On Fatigue During Repeated Resistance Exercise In Recreationally Active Women

Carnosine is a naturally occurring intramuscular dipeptide that is thought to attenuate fatigue during high-intensity exercise. Carnosine content is influenced by various factors, including gender and diet. Despite research reporting that carnosine content is lower in women compared to men and lower in vegetarians compared to omnivores, no investigations have examined carnosine content in women based on dietary protein intake and its effect on muscle fatigue. Twenty recreationally active women were assigned to either a high (HI; n = 5), moderate (MOD; n = 10), or low (LO; n = 5) group based upon intramuscular carnosine content of the vastus lateralis. Each participant underwent two unilateral maximal voluntary isometric contractions (MVIC) of the knee extensors separated by an isokinetic exercise protocol consisting of five sets of 50 repeated maximal unilateral contractions. Magnitude-based inferences were used to analyze group differences. Percent decline in rate of force development and peak torque (PT) during the MVICs and changes in PT and mean torque during the muscle-fatiguing protocol were lower in HI compared to both MOD and LO. Additionally, absolute and relative dietary protein intake were greater in HI compared to MOD or LO. Results indicated that greater intramuscular carnosine content was reflective of greater dietary protein intake and that individuals with higher carnosine content displayed a greater attenuation of fatigue compared to those with lower carnosine

Β-Alanine Supplementation Elevates Intramuscular Carnosine Content And Attenuates Fatigue In Men And Women Similarly But Does Not Change Muscle L-Histidine Content

β-Alanine (BA) supplementation results in elevated intramuscular carnosine content, enhancing buffering capacity during intense exercise. Although men have greater muscle carnosine content than women, elevations still appear to occur despite high baseline levels. Recent research has suggested that BA supplementation may also reduce muscle L-histidine. Thus, the purpose of this investigation was to compare 28 days of BA (6 g·d−1) supplementation in men and women on performance and muscle carnosine, L-histidine, and BA. We hypothesized that supplementation would result in similar elevations in carnosine and performance between sexes and decrease L-histidine. Twenty-six men and women were assigned either BA or placebo (PLA). At baseline, a trend toward greater carnosine (P =.069) was observed in men, and intramuscular BA content was significantly (P ≤.05) greater in men. Statistical analysis was performed using magnitude-based inferences. Changes in muscle carnosine were likely and very likely greater after BA supplementation compared with PLA in men and women, respectively, but changes were unclear between sexes (mean sex difference: 2.50 ± 4.30 mmol·kg−1 ww). The attenuation of exercise fatigue was likely greater in BA compared with PLA, but the change was unclear between sexes (mean sex difference: 14.0 ± 39.0 Nm). Changes in muscle BA following supplementation was unclear in men, likely elevated in women, but unclear between sexes (mean sex difference: 0.03 ± 0.42 mmol·kg−1 ww). Changes in muscle L-histidine were unclear in men and women, and unclear between sexes (mean sex difference: 0.09 ± 0.13 mmol·kg−1 ww). In conclusion, BA supplementation increased muscle carnosine and attenuated fatigue in men and women similarly but did not reduce muscle L-histidine

The Effect Of Polyphenols On Cytokine And Granulocyte Response To Resistance Exercise

This study examined the effect of resistance exercise on the production, recruitment, percentage, and adhesion characteristics of granulocytes with and without polyphenol (PPB) supplementation. Thirty-eight untrained men were randomized into three groups: PPB (n = 13, 21.8 ± 2.5 years, 171.2 ± 5.5 cm, 71.2 ± 8.2 kg), placebo (PL; n = 15, 21.6 ± 2.5 years, 176.5 ± 4.9 cm, 84.0 ± 15.7 kg), or control (CON; n = 10, 23.3 ± 4.3 years, 173.7 ± 12.6 cm, 77.3 ± 16.3 kg). Blood samples were obtained pre (PRE), immediately (IP), 1 h (1H), 5 h (5H), 24 h (24H), 48 h (48H), and 96 h (96H) postresistance exercise (PPB/PL) or rest (CON). Fine-needle biopsies were obtained from the vastus lateralis at PRE, 1H, 5H, and 48H. Plasma concentrations and intramuscular content of interleukin-8 (IL-8), granulocyte (G-CSF), and granulocyte–macrophage colony stimulating factor (GM-CSF) were analyzed via multiplex assays. Changes in relative number of circulating granulocytes and adhesion receptor (CD11b) were assessed using flow cytometry. Intramuscular IL-8 was significantly elevated at 1H, 5H, and 48H (P \u3c 0.001). Area under the curve analysis indicated a greater intramuscular IL-8 content in PL than PPB (P = 0.011). Across groups, circulating G-CSF was elevated from PRE at IP (P \u3c 0.001), 1H (P = 0.011), and 5H (P = 0.025), while GM-CSF was elevated at IP (P \u3c 0.001) and 1H (P = 0.007). Relative number of granulocytes was elevated at 1H (P \u3c 0.001), 5H (P \u3c 0.001), and 24H (P = 0.005, P = 0.006) in PPB and PL, respectively. Across groups, granulocyte CD11b expression was upregulated from PRE to IP (P \u3c 0.001) and 1H (P = 0.015). Results indicated an increase in circulating CD11b on granulocytes, and IL-8 within the muscle following intense resistance exercise. Polyphenol supplementation may attenuate the IL-8 response, however, did not affect granulocyte percentage and adhesion molecule expression in peripheral blood following resistance exercise

Post-Resistance Exercise Ingestion Of Milk Protein Attenuates Plasma Tnfα And Tnfr1 Expression On Monocyte Subpopulations

Attenuating TNFα/TNFr1 signaling in monocytes has been proposed as a means of mitigating inflammation. The purpose of this study was to examine the effects of a milk protein supplement on TNFα and monocyte TNFr1 expression. Ten resistance-trained men (24.7 ± 3.4 years; 90.1 ± 11.3 kg; 176.0 ± 4.9 cm) ingested supplement (SUPP) or placebo (PL) immediately post-exercise in a randomized, cross-over design. Blood samples were obtained at baseline (BL), immediately (IP), 30-min (30P), 1-h (1H), 2-h (2H), and 5-h (5H) post-exercise to assess plasma concentrations of myoglobin; tumor necrosis factor-alpha (TNFα); and expression of tumor necrosis factor receptor 1 (TNFr1) on classical, intermediate, and non-classical monocytes. Magnitude-based inferences were used to provide inferences on the true effects of SUPP compared to PL. Plasma TNFα concentrations were “likely attenuated” (91.6% likelihood effect) from BL to 30P in the SUPP group compared with PL (d = 0.87; mean effect: 2.3 ± 2.4 pg mL−1). TNFr1 expressions on classical (75.9% likelihood effect) and intermediate (93.0% likelihood effect) monocytes were “likely attenuated” from BL to 2H in the SUPP group compared with PL (d = 0.67; mean effect: 510 ± 670 RFU, and d = 1.05; mean effect: 2500 ± 2300 RFU, respectively). TNFr1 expression on non-classical monocytes was “likely attenuated” (77.6% likelihood effect) from BL to 1H in the SUPP group compared with PL (d = 0.69; mean effect: 330 ± 430 RFU). Ingestion of a milk protein supplement immediately post-exercise appears to attenuate both plasma TNFα concentrations and TNFr1 expression on monocyte subpopulations in resistance-trained men

Effects Of Supine Rest Duration On Ultrasound Measures Of The Vastus Lateralis

Introduction: Due to the potential for intramuscular fluid shifts from changing body position, researchers often utilize a 10- to 15-min period of supine rest as a standardizing procedure prior to ultrasound assessment of the lower limbs. However, no previous research has observed the changes in muscle morphological characteristics via ultrasonography of the lower limbs depending on the length of time of supine rest to determine whether 10–15 min of supine rest is necessary. The aim of this study was to examine changes in muscle morphology of the vastus lateralis (VL) at various time-points over the course of 15 min of supine rest. Methods: Muscle thickness (MT), cross-sectional area (CSA) and echo intensity (EI) of the VL were assessed in 24 adults at four time-points including the following: immediately upon moving from a standing to supine position (T0), after 5 (T5), 10 (T10) and 15 min (T15) of lying in a supine position. Results: CSA significantly decreased from T0 to T10 (P = 0·001) and T15 (P\u3c0·001), with no difference between any other time-points (P = 0·055–0·666). However, the reported changes in CSA did not exceed the standard error of the measurement for this procedure. No significant differences between any time-points for MT (P = 0·726–0·966) or EI (P = 0·061–0·783) were observed. Discussion: These findings suggest extended periods of supine rest may not be needed to obtain consistent muscle morphological measurements of the VL using ultrasonography

The Effect of Post-Resistance Exercise Amino Acids on Plasma MCP-1 and CCR2 Expression

The recruitment and infiltration of classical monocytes into damaged muscle is critical for optimal tissue remodeling. This study examined the effects of an amino acid supplement on classical monocyte recruitment following an acute bout of lower body resistance exercise. Ten resistance-trained men (24.7 ˘ 3.4 years; 90.1 ˘ 11.3 kg; 176.0 ˘ 4.9 cm) ingested supplement (SUPP) or placebo (PL) immediately post-exercise in a randomized, cross-over design. Blood samples were obtained at baseline (BL), immediately (IP), 30-min (30P), 1-h (1H), 2-h (2H), and 5-h (5H) post-exercise to assess plasma concentrations of monocyte chemoattractant protein 1 (MCP-1), myoglobin, cortisol and insulin concentrations; and expressions of C-C chemokine receptor-2 (CCR2), and macrophage-1 antigen (CD11b) on classical monocytes. Magnitude-based inferences were used to provide inferences on the true effects of SUPP compared to PL. Changes in myoglobin, cortisol, and insulin concentrations were similar between treatments. Compared to PL, plasma MCP-1 was “very likely greater” (98.1% likelihood effect) in SUPP at 2H. CCR2 expression was “likely greater” at IP (84.9% likelihood effect), “likely greater” at 1H (87.7% likelihood effect), “very likely greater” at 2H (97.0% likelihood effect), and “likely greater” at 5H (90.1% likelihood effect) in SUPP, compared to PL. Ingestion of SUPP did not influence CD11b expression. Ingestion of an amino acid supplement immediately post-exercise appears to help maintain plasma MCP-1 concentrations and augment CCR2 expression in resistance trained men

Comparisons In The Recovery Response From Resistance Exercise Between Young And Middle-Aged Men

Gordon, JA III, Hoffman, JR, Arroyo, E, Varanoske, AN, Coker, NA, Gepner, Y, Wells, AJ, Stout, JR, and Fukuda, DH. Comparisons in the recovery response from resistance exercise between young and middle-aged men. J Strength Cond Res 31(12): 3454–3462, 2017—The purpose of this study was to compare the effects of a bout of high-volume isokinetic resistance exercise protocol (HVP) on lower-body strength and markers of inflammation and muscle damage during recovery between young and middle-aged adult men. Nineteen recreationally trained men were classified as either a young adult (YA: 21.8 6 2.0 years; 90.7 6 11.6 kg) or a middle-aged adult (MA: 47.0 6 4.4 years; 96.0 6 21.5 kg) group. The HVP consisted of 8 sets of 10 repetitions, with 1 minute of rest between each set, performed on an isokinetic dynamometer at 608$s21. Maximal voluntary isometric contractions and isokinetic peak torque (PKT) and average torque (AVGT) (measured at 2408 and 608$s21, respectively) were assessed at baseline (BL), immediately post (IP), 120 minutes, 24, and 48 hours after HVP. Blood was obtained at BL, IP, 30, 60, 120 minute, 24, and 48 hours after HVP to assess muscle damage and inflammation. All performance data were analyzed using repeated measures analysis of covariance, whereas all inflammatory and muscle damage markers were analyzed using a 2-way (time 3 group) repeated measures analysis of variance. Results revealed no between-group differences for PKT, AVGT, or rate of torque development at 200 ms (RTD200). No between-group differences in myoglobin, creatine kinase, C-reactive protein, or interleukin-6 were observed. Although BL differences in muscle performance were observed between YA and MA, no between-group differences were noted in performance recovery measures from high-volume isokinetic exercise in recreationally trained men. These results also indicate that the inflammatory and muscle damage response from high-volume isokinetic exercise is similar between recreationally trained, young, and middle-aged adult men