Tumor necrosis factor-alpha and soluble TNF-alpha receptor responses in young vs. middle-aged males following eccentric exercise

The obesity paradox: Retinopathy, obesity, and circulating risk markers in youth with type 2 diabetes in the TODAY Study

AIM

To understand the relationship of obesity and 27 circulating inflammatory biomarkers to the prevalence of non-proliferative diabetic retinopathy (NPDR) in youth with type 2 diabetes.

METHODS

Youth with type 2 diabetes who participated in the TODAY (Treatment Options for Type 2 Diabetes in Adolescents and Youth) study were followed for 2-6.5 years. Digital fundus photographs were obtained in the last year of the study. Blood samples during the study were processed for inflammatory biomarkers, and these were correlated with obesity tertiles and presence of retinopathy.

RESULTS

Higher BMI was associated with an increase in circulating levels of metabolic biomarkers including high sensitivity C-reactive protein (hsCRP), plasminogen activator inhibitor 1 (PAI-1), fibrinogen, LDL-cholesterol (LDL-C) and Apolipoprotein B (ApoB), tumor necrosis factor receptors 1 and 2 (TNFR-1 and -2), interleukin 6 (IL-6), E-selectin, and homocysteine, as well as a decrease in the metabolic risk markers HDL-cholesterol (HDLC), and insulin-like growth factor binding protein 1 (IGFBP-1). Although NPDR risk decreased with increasing obesity, it was not associated with any of the measured biomarkers.

CONCLUSIONS

Circulating levels of measured biomarkers did not elucidate the "obesity paradox" of decreased NPDR in the most obese participants in the TODAY study.

TRIAL REGISTRATION

clinicaltrials.govNCT00081328.

Immunosenescence in Childhood Cancer Survivors and in Elderly: A Comparison and Implication for Risk Stratification

The population of childhood cancer survivors (CCS) has grown rapidly in recent decades. Although cured of their original malignancy, these individuals are at increased risk of serious late effects, including age-associated complications. An impaired immune system has been linked to the emergence of these conditions in the elderly and CCS, likely due to senescent immune cell phenotypes accompanied by low-grade inflammation, which in the elderly is known as "inflammaging." Whether these observations in the elderly and CCS are underpinned by similar mechanisms is unclear. If so, existing knowledge on immunosenescent phenotypes and inflammaging might potentially serve to benefit CCS. We summarize recent findings on the immune changes in CCS and the elderly, and highlight the similarities and identify areas for future research. Improving our understanding of the underlying mechanisms and immunosenescent markers of accelerated immune aging might help us to identify individuals at increased risk of serious health complications.

Age Differences in Recovery Rate Following an Aerobic-Based Exercise Protocol Inducing Muscle Damage Among Amateur, Male Athletes

Purpose: Compare recovery rates between active young (Y) and middle-aged (MA) males up to 48H post aerobically based, exercise-induced muscle damage (EIMD) protocol. A secondary aim was to explore the relationships between changes in indices associated with EIMD and recovery throughout this timeframe.

Methods: Twenty-eight Y (n = 14, 26.1 ± 2.9y, 74.5 ± 9.3 kg) and MA (n = 14, 43.6 ± 4.1y, 77.3 ± 12.9 kg) physically active males, completed a 60-min downhill running (DHR) on a treadmill at −10% incline and at 65% of maximal heart rate (HR). Biochemical, biomechanical, psychological, force production and muscle integrity (using MRI diffusion tensor imaging) markers were measured at baseline, immediately-post, and up to 48H post DHR.

Results: During the DHR, HR was lower (p < 0.05) in MA compared to Y, but running pace and distance covered were comparable between groups. No statistical or meaningful differences were observed between groups for any of the outcomes. Yet, Significant (p < 0.05) time-effects within each group were observed: markers of muscle damage, cadence and perception of pain increased, while TNF-a, isometric and dynamic force production and stride-length decreased. Creatine-kinase at 24H-post and 48H-post were correlated (p < 0.05, r range = −0.57 to 0.55) with pain perception, stride-length, and cadence at 24H-post and 48H-post. Significant (p < 0.05) correlations were observed between isometric force production at all time-points and IL-6 at 48H-post DHR (r range = −0.62 to (−0.74).

Conclusion: Y and MA active male amateur athletes recover in a comparable manner following an EIMD downhill protocol. These results indicate that similar recovery strategies can be used by trainees from both age groups following an aerobic-based EIMD protocol.

Influence of muscle depth and thickness on ultrasound echo intensity of the vastus lateralis

BACKGROUND

Ultrasonography is used to evaluate muscle quality (i.e. echo intensity [EI]), but an attenuation of ultrasound waves occurs in deeper tissues, potentially affecting these measures.

PURPOSE

To determine whether muscle thickness (MT) affects EI and if EI varies between the superficial and deep portions of the muscle.

MATERIALS AND METHODS

MT, EI, subcutaneous adipose tissue thickness (SAT), tissue depth (DIS_DEEP), and EI of the overall (EI_FULL) as well as deep (EI_DEEP) and superficial (EI_SUPF) portions of the vastus lateralis (VL) were assessed in 33 resistance-trained males using ultrasonography. The difference (EI_DIFF) between EI_SUPF and EI_DEEP was calculated. Mean differences between EI_FULL, EI_SUPF, and EI_DEEP were analyzed using a repeated-measures analysis of variance (ANOVA). Relationships between measures of muscle depth/ thickness and EI were examined using Pearson's r.

RESULTS

EI_SUPF was greater than EI_DEEP (P < 0.001) and EI_FULL (P < 0.001). MT was negatively correlated with EI_FULL (P < 0.001) and positively correlated with EI_DIFF (P < 0.001). SAT was not correlated with any EI measure, but DIS_DEEP was positively correlated with EI_DIFF (P < 0.001).

CONCLUSION

EI of the VL is heterogeneous, as the deeper portion produces lower values than the superficial portion. Thicker muscles present lower EI but have greater discrepancies in EI between the superficial and deep portions. Although SAT was not correlated with EI, DIS_DEEP was related to EI_DIFF, demonstrating that the combination of MT and SAT should be considered when evaluating muscle quality. Future research is necessary to determine if changes in EI following resistance training are driven by increases in MT.

The influence of age on the recovery from worksite resistance exercise in career firefighters

Resistance exercise is an important strategy to reduce injuries and improve performance in the fire service. However, given the large age range of firefighters, it is important to determine if age influences their recovery following an acute bout of resistance exercise.

PURPOSE

To examine the changes in indirect markers of muscle damage in young and older firefighters following a feasible worksite resistance exercise routine.

METHODS

Nineteen young (25.5 ± 3.4 years) and 19 older male career firefighters (50.3 ± 3.5 years) completed pre-testing, an acute bout of resistance exercise, and post-testing at 24, 48, and 72 h post-exercise at their fire station. Prior to all testing, firefighters completed a work-related fatigue (WRF) questionnaire to account for potential unanticipated differences in previous shift workloads. Testing included perceived muscle soreness, ultrasonography to quantify muscle size and echo intensity (EI) of the vastus lateralis (VL) and biceps brachii (BB), countermovement jump (CMJ) height and velocity, upper body (UB) peak force (PF), lower body (LB) PF and rapid force, and electromyographic (EMG) amplitude of the VL. The resistance training session included 3 sets of 8-10 repetitions of a deadlift, shoulder press, lunge, and upright row exercise at 80% 1-RM. All recovery variables were analyzed using a linear mixed model, controlling for WRF.

RESULTS

There was no interaction (age × time) for any of the variables and a similar training volume were completed between groups (P ≥ 0.171). Muscle soreness, CMJ height and velocity, UB PF, LB rapid force and EMG amplitude at later time intervals (100-200 ms), and VL and BB muscle size were altered from baseline (P ≤ 0.044) for 48, 24, 48, 72, and 72 h post-exercise, respectively. Young firefighters exhibited greater CMJ height and velocity, LB PF, LB rapid force (200 ms), and lower VL EI values than the older firefighters (P ≤ 0.047).

CONCLUSIONS

Age did not influence the recovery from an acute bout of worksite resistance exercise in firefighters. However, UB muscle strength, CMJ performance, and LB rapid force production were reduced 24-72 h post-exercise. Appropriately scheduled and chronic on-duty resistance training may mitigate these decrements.

Muscle Quality, Measured by Ultrasound-Derived Corrected Echo Intensity, Does not Affect Changes in Cross-sectional Area of the Vastus Lateralis Following Recumbent Rest

Objective:

Recumbent rest elicits a decrease in muscle size of the lower extremity, but the extent of decrease may be related to differences in muscle quality. This could have implications for ultrasound-derived measures of muscle size, particularly in individuals with a large proportion of intramuscular contractile elements. The research objective was to determine whether decreases in muscle size following recumbent rest are related to ultrasound-derived corrected echo intensity in resistance-trained males.

Methods:

Cross-sectional area (CSA), echo intensity (EI), subcutaneous fat thickness (SFT), and EI corrected for SFT (EICor) of the vastus lateralis (VL) were measured via ultrasonography in 30 resistance-trained males. Measures were obtained immediately following recumbency (T0) and 15 minutes after recumbency (T15). The association between EICor and percentage change in CSA (%ΔCSA) from T0 to T15 was examined. Comparisons of morphological characteristics were examined between a subset of participants with the lowest (LO; n = 10; <33rd percentile) and highest (HI; n = 10; >66th percentile) EICor.

Results:

EICor was not correlated with %ΔCSA ( P = .151), and the decrease in CSA from T0 to T15 did not differ between the LO and HI groups.

Conclusions:

Muscle quality (EICor) is not related to the decrease in CSA of the VL following recumbent rest among resistance-trained, young males. The time frame of muscle CSA acquisition should not differ based solely on differences in muscle quality.

Exercise-induced muscle damage: mechanism, assessment and nutritional factors to accelerate recovery

There have been a multitude of reviews written on exercise-induced muscle damage (EIMD) and recovery. EIMD is a complex area of study as there are a host of factors such as sex, age, nutrition, fitness level, genetics and familiarity with exercise task, which influence the magnitude of performance decrement and the time course of recovery following EIMD. In addition, many reviews on recovery from exercise have ranged from the impact of nutritional strategies and recovery modalities, to complex mechanistic examination of various immune and endocrine signaling molecules. No one review can adequately address this broad array of study. Thus, in this present review, we aim to examine EIMD emanating from both endurance exercise and resistance exercise training in recreational and competitive athletes and shed light on nutritional strategies that can enhance and accelerate recovery following EIMD. In addition, the evaluation of EIMD and recovery from exercise is often complicated and conclusions often depend of the specific mode of assessment. As such, the focus of this review is also directed at the available techniques used to assess EIMD.

Aging and Recovery After Resistance-Exercise-Induced Muscle Damage: Current Evidence and Implications for Future Research

Aging is anecdotally associated with a prolonged recovery from resistance training, though current literature remains equivocal. This brief review considers the effects of resistance training on indirect markers of muscle damage and recovery (i.e., muscle soreness, blood markers, and muscle strength) in older males. With no date restrictions, four databases were searched for articles relating to aging, muscle damage, and recovery. Data from 11 studies were extracted for review. Of these, four reported worse symptoms in older compared with younger populations, while two have observed the opposite, and the remaining studies (n = 6) proposed no differences between age groups. It appears that resistance training can be practiced in older populations without concern for impaired recovery. To improve current knowledge, researchers are urged to utilize more ecologically valid muscle-damaging bouts and investigate the mechanisms which underpin the recovery of muscle soreness and strength after exercise in older populations.

The Effect of Orally Dosed Levagen+™ (palmitoylethanolamide) on Exercise Recovery in Healthy Males-A Double-Blind, Randomized, Placebo-Controlled Study

The aim of this study was to evaluate the effect of palmitoylethanolamide (PEA), a cannabimimetic compound and lipid messenger, on recovery from muscle damaging exercise. Twenty-eight healthy young male participants attended the laboratory four times on subsequent days. In the first visit, baseline characteristics were recorded before participants were randomized to consume either liquid PEA (167.5 mg Levagen+ with 832.5 mg maltodextrin) or a matched placebo (1 g maltodextrin) drink. Leg press exercise consisted of four sets at 80% of one repetition maximum followed by a performance set. Muscle soreness, thigh circumference, blood lactate concentration, biomarkers of muscle damage and inflammation, and transcription factor pathways were measured pre- and immediately post-exercise and again at 1, 2, 3, 24, 48, and 72 h post-exercise. The leg press exercise increased (p < 0.05) blood lactate concentration and induced muscle damage as evidenced by increased muscle soreness, thigh circumference, biomarkers of muscle damage, and concentrations of tumor necrosis factor-α. PEA reduced (p < 0.05) myoglobin and blood lactate concentrations and increased protein kinase B phosphorylation following exercise. Taken together, these results indicate PEA supplementation may aid in muscle recovery from repeat bouts of exercise performed within a short duration by reducing myoglobin and lactate concentration.

Eccentric exercise results in a prolonged increase in interleukin-6 and tumor necrosis factor-α levels in rat skeletal muscle

Interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) are well-known cytokines with pro-inflammatory capabilities, and have been shown to be involved in adaptation to exercise as multifaceted myokines. However, the precise role of IL-6 and TNF-α during exercise-induced skeletal muscle injury and subsequent repair processes is not fully understood. In this study, IL-6 and TNF-α were examined in soleus muscles at the gene and protein levels using in situ hybridization and immunohistochemical staining, respectively, and serum levels of IL-6 and TNF-α were determined before and after a 90-min downhill running session in rats. There were no changes in serum levels of IL-6 and TNF-α after exercise, but IL-6 and TNF-α mRNA increased and maintained high expression in muscles for 1-2 weeks after exercise. IL-6 and TNF-a mRNAs were identified in both the cytoplasm and the nuclei of myocytes, as well as in invading inflammatory cells. IL-6 and TNF-α protein mainly distributed in cytoplasm unevenly and had a prolonged expression until 2 weeks after eccentric exercise. Our results demonstrate that there is increased IL-6 and TNF-α expression in skeletal muscle that is induced by eccentric exercise and that the high expression of IL-6 and TNF-α in the long-term phase after eccentric exercise may be more involved in the subsequent recovery of damaged muscle.

Effects of Rest Position on Morphology of the Vastus Lateralis and Its Relationship with Lower-Body Strength and Power

Ultrasonography of the lower body typically encompasses supine rest due to fluid shifts affecting tissue size and composition. However, vastus lateralis (VL) examination is completed in the lateral recumbent position, and this positional change may influence morphology and its ability to predict function. This study aimed to examine the effect of position on VL morphology and its relationship with lower-body performance. Cross-sectional area (CSA), muscle thickness (MT), pennation angle (PA), echo intensity (UnCorEI), subcutaneous adipose tissue thickness (SFT), and echo intensity corrected for SFT (CorEI) were assessed in 31 resistance-trained males (23.0 ± 2.1 yrs; 1.79 ± 0.08 m; 87.4 ± 11.7 kg) immediately after transitioning from standing to supine (IP), after 15 min of standing (ST), and after 15 min of rest in three recumbent positions: supine (SUP), dominant lateral recumbent (DLR), non-dominant lateral recumbent (NDLR). Participants also completed unilateral vertical jumps, isometric/isokinetic tests, and a one-repetition maximum leg press. CSA, MT, PA, and SFT were greater in ST compared to NDLR, DLR, and SUP (p < 0.05). CSA, UnCorEI, and CorEI were different between recumbent positions; however no differences were observed for MT, PA, and SFT. Different magnitudes of relationships were observed between muscle morphological characteristics measured after rest in different positions and performance variables. Muscle morphology in IP generally appears to be the best predictor of performance for most variables, although utilizing the NDLR and DLR positions may provide comparable results, whereas morphology measured in ST and SUP provide weaker relationships with physical performance. IP also requires less time and fewer requirements on the technician and subject, thus researchers should consider this positioning for VL examination.

Exaggerated post exercise hypotension following concentric but not eccentric resistance exercise: Implications for metabolism

Post exercise hypotension (PEH) is primarily attributed to post-exercise vasodilation via central and peripheral mechanisms. However, the specific contribution of metabolic cost during exercise, independent of force production, is less clear. This study aimed to use isolated concentric and eccentric exercise to examine the role of metabolic activity in eliciting PEH, independent of total work. Twelve participants (6 male) completed upper and lower body concentric (CONC), eccentric (ECC), and traditional (TRAD) exercise sessions matched for work (3 × 10 in TRAD and 3 × 20 in CONC and ECC; all at 65% 1RM). Blood pressure was collected at baseline and every 15 min after exercise for 120 min. Brachial blood flow and vascular conductance were also assessed at baseline, immediately after exercise, and every 30 min after exercise. ⩒O₂ was lower during ECC compared to CONC and TRAD (-2.7 mL/Kg/min ± 0.4 and -2.2 mL/Kg/min ± 0.4, respectively p < 0.001). CONC augmented the PEH response (Peak ΔMAP -3.3 mmHg ± 0.9 [mean ± SE], p = 0.006) through 75 min of recovery and ECC elicited a post-exercise hypertensive response through 120 min of recovery (Peak ΔMAP +4.5 mmHg ± 0.8, p < 0.001). CONC and TRAD elicited greater increases in brachial blood flow post exercise than ECC (Peak Δ brachial flow +190.4 mL/min ± 32.3, +202.3 mL/min ± 39.2, and 69.6 mL/min ± 19.8, respectively, p ≤ 0.005), while conductance increased immediately post exercise in all conditions and then decreased throughout recovery following ECC (-32.9 mL/min/mmHg ± 9.3, p = 0.005). These data suggest that more metabolically demanding concentric exercise augments PEH compared to work-matched eccentric exercise.