Patrick S. Tucker

Clinical and research markers of oxidative stress in chronic kidney disease

Abstract Context: Kidney-related pathologies have increasing prevalence rates, produce a considerable financial burden, and are characterized by elevated levels of oxidative stress (OS). Objective: This review examines relationships between chronic kidney disease (CKD) and markers of OS and antioxidant status (AS). Methods: A systematic review of MEDLINE-indexed clinical trials, randomized controlled trials and comparative studies that examined OS and AS was performed. Results and conclusion: Several markers emerged as well-suited indicators of OS and AS in CKD: malondialdehyde, F2-isoprostanes, lipid hydroperoxides, asymmetric dimethylarginine, 8-oxo-7,8-dihydro-2′-deoxyguanosine, protein carbonyls, advanced oxidation protein products and glutathione-related activity.

Chronic kidney disease influences multiple systems: describing the relationship between oxidative stress, inflammation, kidney damage, and concomitant disease.

Chronic kidney disease (CKD) is characterized by increased levels of oxidative stress and inflammation. Oxidative stress and inflammation promote renal injury via damage to molecular components of the kidney. Unfortunately, relationships between inflammation and oxidative stress are cyclical in that the inflammatory processes that exist to repair radical-mediated damage may be a source of additional free radicals, resulting in further damage to renal tissue. Oxidative stress and inflammation also have the ability to become systemic, serving to injure tissues distal to the site of original insult. This review describes select mediators in the exacerbatory relationship between oxidative stress, inflammation, and CKD. This review also discusses oxidative stress, inflammation, and CKD as they pertain to the development and progression of common CKD-associated comorbidities. Lastly, the utility of several widely accessible and cost-effective lifestyle interventions and their ability to reduce oxidative stress and inflammation are discussed and recommendations for future research are provided.

Effects of high-intensity interval training on cardiometabolic health: a systematic review and meta-analysis of intervention studies

The current review clarifies the cardiometabolic health effects of high-intensity interval training (HIIT) in adults. A systematic search (PubMed) examining HIIT and cardiometabolic health markers was completed on 15 October 2015. Sixty-five intervention studies were included for review and the methodological quality of included studies was assessed using the Downs and Black score. Studies were classified by intervention duration and body mass index classification. Outcomes with at least 5 effect sizes were synthesised using a random-effects meta-analysis of the standardised mean difference (SMD) in cardiometabolic health markers (baseline to postintervention) using Review Manager 5.3. Short-term (ST) HIIT (<12 weeks) significantly improved maximal oxygen uptake (VO2 max; SMD 0.74, 95% CI 0.36 to 1.12; p<0.001), diastolic blood pressure (DBP; SMD −0.52, 95% CI −0.89 to −0.16; p<0.01) and fasting glucose (SMD −0.35, 95% CI −0.62 to −0.09; p<0.01) in overweight/obese populations. Long-term (LT) HIIT (≥12 weeks) significantly improved waist circumference (SMD −0.20, 95% CI −0.38 to −0.01; p<0.05), % body fat (SMD −0.40, 95% CI −0.74 to −0.06; p<0.05), VO2 max (SMD 1.20, 95% CI 0.57 to 1.83; p<0.001), resting heart rate (SMD −0.33, 95% CI −0.56 to −0.09; p<0.01), systolic blood pressure (SMD −0.35, 95% CI −0.60 to −0.09; p<0.01) and DBP (SMD −0.38, 95% CI −0.65 to −0.10; p<0.01) in overweight/obese populations. HIIT demonstrated no effect on insulin, lipid profile, C reactive protein or interleukin 6 in overweight/obese populations. In normal weight populations, ST-HIIT and LT-HIIT significantly improved VO2 max, but no other significant effects were observed. Current evidence suggests that ST-HIIT and LT-HIIT can increase VO2 max and improve some cardiometabolic risk factors in overweight/obese populations.

The relationships between internal and external training load models during basketball training.

Abstract Scanlan, AT, Wen, N, Tucker, PS, and Dalbo, VJ. The relationships between internal and external training load models during basketball training. J Strength Cond Res 28(9): 2397–2405, 2014—The present investigation described and compared the internal and external training loads during basketball training. Eight semiprofessional male basketball players (mean ± SD, age: 26.3 ± 6.7 years; stature: 188.1 ± 6.2 cm; body mass: 92.0 ± 13.8 kg) were monitored across a 7-week period during the preparatory phase of the annual training plan. A total of 44 total sessions were monitored. Player session ratings of perceived exertion (sRPE), heart rate, and accelerometer data were collected across each training session. Internal training load was determined using the sRPE, training impulse (TRIMP), and summated-heart-rate-zones (SHRZ) training load models. External training load was calculated using an established accelerometer algorithm. Pearson product-moment correlations with 95% confidence intervals (CIs) were used to determine the relationships between internal and external training load models. Significant moderate relationships were observed between external training load and the sRPE (r42 = 0.49, 95% CI = 0.23–0.69, p < 0.001) and TRIMP models (r42 = 0.38, 95% CI = 0.09–0.61, p = 0.011). A significant large correlation was evident between external training load and the SHRZ model (r42 = 0.61, 95% CI = 0.38–0.77, p < 0.001). Although significant relationships were found between internal and external training load models, the magnitude of the correlations and low commonality suggest that internal training load models measure different constructs of the training process than the accelerometer training load model in basketball settings. Basketball coaching and conditioning professionals should not assume a linear dose-response between accelerometer and internal training load models during training and are recommended to combine internal and external approaches when monitoring training load in players.

The effects of age on skeletal muscle and the phosphocreatine energy system: can creatine supplementation help older adults

Creatine supplementation has been found to significantly increase muscle strength and hypertrophy in young adults (≤ 35 yr) particularly when consumed in conjunction with a resistance training regime. Literature examining the efficacy of creatine supplementation in older adults (55-82 yr) suggests creatine to promote muscle strength and hypertrophy to a greater extent than resistance training alone. The following is a review of literature reporting on the effects of creatine supplementation on intramuscular high energy phosphates, skeletal muscle morphology and quality of life in older adults. Results suggest creatine supplementation to be a safe, inexpensive and effective nutritional intervention, particularly when consumed in conjunction with a resistance training regime, for slowing the rate of muscle wasting that is associated with aging. Physicians should strongly consider advising older adults to supplement with creatine and to begin a resistance training regime in an effort to enhance skeletal muscle strength and hypertrophy, resulting in enhanced quality of life.

Effects of Light Intensity Activity on CVD Risk Factors: A Systematic Review of Intervention Studies.

The effects of light intensity physical activity (LIPA) on cardiovascular disease (CVD) risk factors remain to be established. This review summarizes the effects of LIPA on CVD risk factors and CVD-related markers in adults. A systematic search of four electronic databases (PubMed, Academic Search Complete, SPORTDiscus, and CINAHL) examining LIPA and CVD risk factors (body composition, blood pressure, glucose, insulin, glycosylated hemoglobin, and lipid profile) and CVD-related markers (maximal oxygen uptake, heart rate, C-reactive protein, interleukin-6, tumor necrosis factor-alpha, and tumor necrosis factor receptors 1 and 2) published between 1970 and 2015 was performed on 15 March 2015. A total of 33 intervention studies examining the effect of LIPA on CVD risk factors and markers were included in this review. Results indicated that LIPA did not improve CVD risk factors and CVD-related markers in healthy individuals. LIPA was found to improve systolic and diastolic blood pressure in physically inactive populations with a medical condition. Reviewed studies show little support for the role of LIPA to reduce CVD risk factors. Many of the included studies were of low to fair study quality and used low doses of LIPA. Further studies are needed to establish the value of LIPA in reducing CVD risk.

The influence of physical and cognitive factors on reactive agility performance in men basketball players

Abstract This study explored the influence of physical and cognitive measures on reactive agility performance in basketball players. Twelve men basketball players performed multiple sprint, Change of Direction Speed Test, and Reactive Agility Test trials. Pearson’s correlation analyses were used to determine relationships between the predictor variables (stature, mass, body composition, 5-m, 10-m and 20-m sprint times, peak speed, closed-skill agility time, response time and decision-making time) and reactive agility time (response variable). Simple and stepwise regression analyses determined the individual influence of each predictor variable and the best predictor model for reactive agility time. Morphological (r = –0.45 to 0.19), sprint (r = –0.40 to 0.41) and change-of-direction speed measures (r = 0.43) had small to moderate correlations with reactive agility time. Response time (r = 0.76, P = 0.004) and decision-making time (r = 0.58, P = 0.049) had large to very large relationships with reactive agility time. Response time was identified as the sole predictor variable for reactive agility time in the stepwise model (R2 = 0.58, P = 0.004). In conclusion, cognitive measures had the greatest influence on reactive agility performance in men basketball players. These findings suggest reaction and decision-making drills should be incorporated in basketball training programmes.

Molecular attributes of human skeletal muscle at rest and after unaccustomed exercise: an age comparison.

Roberts, MD, Kerksick, CM, Dalbo, VJ, Hassell, SE, Tucker, PS, and Brown, R. Molecular attributes of human skeletal muscle at rest and after unaccustomed exercise: an age comparison. J Strength Cond Res 24(5): 1161-1168, 2010-The current study examined muscle DNA and protein concentrations ([ ]) and the [RNA] (assumed to represent translational capacity), [RNA]:[DNA] (assumed to represent transcriptional efficiency) and [protein]:[RNA] (assumed to represent translational efficiency) in younger vs. older participants during a resting state. Further, changes in muscle [DNA], translational capacity, and transcriptional efficiency were analyzed 24 hours after an unaccustomed resistance exercise bout. Younger (20.9 ± 0.5 years, 84.0 ± 5.2 kg, 26.6 ± 1.8 kg·m−2; n = 13) and older men (67.6 ± 1.3 years, 88.7 ± 4.8 kg, 28.6 ± 1.4 kg·m−2; n = 13) reported to the laboratory and completed an unaccustomed bout of lower-body resistance training (i.e., 3 sets of 10 repetitions at 80% 1 repetition maximum for Smith squat, leg press, and leg extensions). Muscle biopsies from the vastus lateralis were obtained before and 24 hours after exercise. Baseline [RNA], [DNA], [protein], and [RNA]:[DNA] were not different between age groups (p > 0.05). Baseline [protein]:[RNA] was greater in younger vs. older men (p = 0.045), whereas 24-hour postexercise [RNA]:[DNA] tended to be greater in older men (p = 0.087). These findings suggest that a decrease in the efficiency of translational processes occurs in older human skeletal muscle, whereas global transcriptional processes appear to be unaltered when compared with those in younger men. In lieu of these data, it remains apparent that muscle-protein synthesis is impaired in aging skeletal muscle and effective countermeasures such as resistance exercise and nutritional adequacy must be undertaken by older populations to offset this phenomenon.

Training Mode’s Influence on the Relationships Between Training-Load Models During Basketball Conditioning

PURPOSE To compare perceptual and physiological training-load responses during various basketball training modes. METHODS Eight semiprofessional male basketball players (age 26.3 ± 6.7 y, height 188.1 ± 6.2 cm, body mass 92.0 ± 13.8 kg) were monitored across a 10-wk period in the preparatory phase of their training plan. Player session ratings of perceived exertion (sRPE) and heart-rate (HR) responses were gathered across base, specific, and tactical/game-play training modes. Pearson correlations were used to determine the relationships between the sRPE model and 2 HR-based models: the training impulse (TRIMP) and summated HR zones (SHRZ). One-way ANOVAs were used to compare training loads between training modes for each model. RESULTS Stronger relationships between perceptual and physiological models were evident during base (sRPE-TRIMP r = .53, P < .05; sRPE-SHRZ r = .75, P < .05) and tactical/game-play conditioning (sRPE-TRIMP r = .60, P < .05; sRPE-SHRZ r = .63; P < .05) than during specific conditioning (sRPE-TRIMP r = .38, P < .05; sRPE-SHRZ r = .52; P < .05). Furthermore, the sRPE model detected greater increases (126-429 AU) in training load than the TRIMP (15-65 AU) and SHRZ models (27-170 AU) transitioning between training modes. CONCLUSIONS While the training-load models were significantly correlated during each training mode, weaker relationships were observed during specific conditioning. Comparisons suggest that the HR-based models were less effective in detecting periodized increases in training load, particularly during court-based, intermittent, multidirectional drills. The practical benefits and sensitivity of the sRPE model support its use across different basketball training modes.

The role of the gastrointestinal tract and microbiota on uremic toxins and chronic kidney disease development

It is well-established that uremic toxins are positively correlated with the risk of developing chronic kidney disease and cardiovascular disease. In addition, emerging data suggest that gut bacteria exert an influence over both the production of uremic toxins and the development of chronic kidney disease. As such, modifying the gut microbiota may have the potential as a treatment for chronic kidney disease. This is supported by data that suggest that rescuing microbiota dysbiosis may: reduce uremic toxin production; prevent toxins and pathogens from crossing the intestinal barrier; and, reduce gastrointestinal tract transit time allowing nutrients to reach the microbiota in the distal portion of the gastrointestinal tract. Despite emerging literature, the gut–kidney axis has yet to be fully explored. A special focus should be placed on examining clinically translatable strategies that might encourage improvements to the microbiome, thereby potentially reducing the risk of the development of chronic kidney disease. This review aims to present an overview of literature linking changes to the gastrointestinal tract with microbiota dysbiosis and the development and progression of chronic kidney disease.