Grip and shoulder strength correlation with validated outcome instruments in patients with rotator cuff tears.

HYPOTHESIS/BACKGROUND: The ability to better define preoperatively the extent of rotator cuff (RC) dysfunction is desired. The study's purpose was to prospectively examine the relationships between absolute and percentage loss (affected compared to unaffected) of grip and shoulder strength, and RC dysfunction. METHODS: Forty-seven consecutive patients with proven RC tears participated in this study. Prior to surgery, bilateral strengths of grip, shoulder abduction, and shoulder external rotation (ER) were measured with a handheld dynamometer, and subjective outcome measures were gathered. RC tear size was determined via arthroscopy. Patient-reported outcomes were gathered on the day of the examination or via e-mail following initial evaluation. Descriptive statistics, difference analysis, and correlation coefficients (reported as either direct or negative) were used to analyze data. Grip, abduction and ER strengths, and percentage loss of grip, abduction, and ER strengths (percentage loss affected vs. unaffected), and tear size were analyzed in relation to all of the scores on selected subjective outcome measurement tools. The P value was set at .05. RESULTS: Fair direct correlations were found between grip strength and the Veterans RAND 12-Item Health Survey (VR-12) mental health scores, ER strength and Simple Shoulder Test (SST), abduction strength, and both the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) function score and SST score. Abduction and ER strengths were also found to possess a fair direct correlation. Fair negative correlations were found between the ASES function score and each of the following: percentage loss of abduction strength, percentage loss of ER strength, and tear size in centimeters. Another fair negative correlation was found between the Single Assessment Numerical Evaluation (SANE) score and tear size in centimeters. DISCUSSION: Our findings suggest that as shoulder strength decreases, ipsilateral shoulder RC dysfunction increases. Grip strength was not related to shoulder RC dysfunction. CONCLUSION: Grip strength was not found to correlate with RC tears. Those with decreased abduction and ER strengths and low ASES scores should be considered more likely to have an RC tear.

Low and high carbohydrate isocaloric diets on performance, fat oxidation, glucose and cardiometabolic health in middle age males.

High carbohydrate, low fat (HCLF) diets have been the predominant nutrition strategy for athletic performance, but recent evidence following multi-week habituation has challenged the superiority of HCLF over low carbohydrate, high fat (LCHF) diets, along with growing interest in the potential health and disease implications of dietary choice. Highly trained competitive middle-aged athletes underwent two 31-day isocaloric diets (HCLF or LCHF) in a randomized, counterbalanced, and crossover design while controlling calories and training load. Performance, body composition, substrate oxidation, cardiometabolic, and 31-day minute-by-minute glucose (CGM) biomarkers were assessed. We demonstrated: (i) equivalent high-intensity performance (@∼85%VO2max), fasting insulin, hsCRP, and HbA1c without significant body composition changes across groups; (ii) record high peak fat oxidation rates (LCHF:1.58 ± 0.33g/min @ 86.40 ± 6.24%VO2max; 30% subjects > 1.85 g/min); (iii) higher total, LDL, and HDL cholesterol on LCHF; (iv) reduced glucose mean/median and variability on LCHF. We also found that the 31-day mean glucose on HCLF predicted 31-day glucose reductions on LCHF, and the 31-day glucose reduction on LCHF predicted LCHF peak fat oxidation rates. Interestingly, 30% of athletes had 31-day mean, median and fasting glucose > 100 mg/dL on HCLF (range: 111.68-115.19 mg/dL; consistent with pre-diabetes), also had the largest glycemic and fat oxidation response to carbohydrate restriction. These results: (i) challenge whether higher carbohydrate intake is superior for athletic performance, even during shorter-duration, higher-intensity exercise; (ii) demonstrate that lower carbohydrate intake may be a therapeutic strategy to independently improve glycemic control, particularly in those at risk for diabetes; (iii) demonstrate a unique relationship between continuous glycemic parameters and systemic metabolism.

Ketone Bodies Impact on Hypoxic CO2 Retention Protocol During Exercise.

Exogenous ketone esters have demonstrated the capacity to increase oxygen availability during acute hypoxic exposure leading to the potential application of their use to mitigate performance declines at high altitudes. Voluntary hypoventilation (VH) with exercise reliably reduces oxygen availability and increases carbon dioxide retention without alterations to ambient pressure or gas content. Utilizing a double-blind randomized crossover design, fifteen recreational male distance runners performed submaximal exercise (4 × 5 min; 70% VO2 Max) with VH. An exogenous ketone ester (KME; 573 mg⋅kg-1) or iso-caloric flavor matched placebo (PLA) was consumed prior to exercise. Metabolites, blood gases, expired air, heart rate, oxygen saturation, cognition, and perception metrics were collected throughout. KME rapidly elevated R-ß-hydroxybutyrate and reduced blood glucose without altering lactate production. KME lowered pH, bicarbonate, and total carbon dioxide. VH with exercise significantly reduced blood (SpO2) and muscle (SmO2) oxygenation and increased cognitive mean reaction time and respiratory rate regardless of condition. KME administration significantly elevated respiratory exchange ratio (RER) at rest and throughout recovery from VH, compared to PLA. Blood carbon dioxide (PCO2) retention increased in the PLA condition while decreasing in the KME condition, leading to a significantly lower PCO2 value immediately post VH exercise (IPE; p = 0.031) and at recovery (p = 0.001), independent of respiratory rate. The KME's ability to rapidly alter metabolism, acid/base balance, CO2 retention, and respiratory exchange rate independent of respiratory rate changes at rest, during, and/or following VH exercise protocol illustrates a rapid countermeasure to CO2 retention in concert with systemic metabolic changes.

Dose response of a novel exogenous ketone supplement on physiological, perceptual and performance parameters.

BACKGROUND: Interest into the health, disease, and performance impact of exogenous ketone bodies has rapidly expanded due to their multifaceted physiological and signaling properties but limiting our understanding is the isolated analyses of individual types and dose/dosing protocols. METHODS: Thirteen recreational male distance runners (24.8 ± 9.6 years, 72.5 ± 8.3 kg, VO2max 60.1 ± 5.4 ml/kg/min) participated in this randomized, double-blind, crossover design study. The first two sessions consisted of a 5-km running time trial familiarization and a VO2max test. During subsequent trials, subjects were randomly assigned to one (KS1: 22.1 g) or two (KS2: 44.2 g) doses of beta-hydroxybutyrate (ßHB) and medium chain triglycerides (MCTs) or flavor matched placebo (PLA). Blood R-ßHB, glucose, and lactate concentrations were measured at baseline (0-min), post-supplement (30 and 60 min), post-exercise (+ 0 min, + 15 min). Time, heart rate (HR), rating of perceived exertion (RPE), affect, respiratory exchange ratio, oxygen consumption (VO2), carbon dioxide production, and ventilation were measured during exercise. Cognitive performance was evaluated prior to and post-exercise. RESULTS: KS significantly increased R-ßHB, with more potent and prolonged elevations in KS2, illustrating an administrative and dosing effect. R-ßHB was significantly decreased in KS1 compared to KS2 illustrating a dosing and exercise interaction effect. Blood glucose elevated post-exercise but was unchanged across groups. Blood lactate significantly increased post-exercise but was augmented by KS administration. Gaseous exchange, respiration, HR, affect, RPE, and exercise performance was unaltered with KS administration. However, clear responders and none-responders were indicated. KS2 significantly augmented cognitive function in pre-exercise conditions, while exercise increased cognitive performance for KS1 and PLA to pre-exercise KS2 levels. CONCLUSION: Novel ßHB + MCT formulation had a dosing effect on R-ßHB and cognitive performance, an administrative response on blood lactate, while not influencing gaseous exchange, respiration, HR, affect, RPE, and exercise performance.