Throwing Shoulder Adaptations Are Not Related to Shoulder Injury or Pain: A Preliminary Report.

BACKGROUND: Overhead throwing in baseball and softball athletes induces shoulder adaptations theorized to increase risk of shoulder musculoskeletal injury (MSI) and/or pain due to range of motion (ROM) deficits. HYPOTHESIS: Shoulder ROM adaptations are associated with a higher risk for developing shoulder MSI and pain. STUDY DESIGN: Prospective cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 60 National Collegiate Athletic Association Division I athletes cleared for full athletic participation and free from upper extremity MSI in the last 4 weeks (age, 19.0 ± 1.2 years; weight, 82.1 ± 13.7 kg; height, 178.6 ± 11.2 cm; softball, n = 23; baseball, n = 37). Passive glenohumeral internal rotation (IR), external rotation (ER), and horizontal adduction (HA) ROM were measured with the scapula stabilized and used to categorize participants with/without external rotation gain (ERG), external rotation insufficiency (ERI), glenohumeral internal rotation deficit (GIRD), pathological GIRD, and posterior shoulder tightness (PST) before the competitive season. Groups were then compared to assess the incidence of shoulder MSI prospectively and prevalence of shoulder pain at the initial evaluation. RESULTS: Baseball and softball athletes demonstrated significantly less IR ROM in the dominant shoulder (50.6° ± 9.4°) compared with the nondominant shoulder (59.1° ± 8.6°; P < 0.01) and significantly more ER ROM (dominant, 104.6° ± 12.1°; nondominant, 97.7° ± 12.0°; P < 0.01). Incidence of shoulder MSI was 15% but was not significantly related to any shoulder adaptations. No significant relationship was found between prevalence of pain and any shoulder adaptations in the 27% of athletes with pain. CONCLUSION: Increased ER and decreased IR ROM adaptations in intercollegiate overhead throwing athletes do not appear to be correlated to risk of shoulder MSI or pain. CLINICAL RELEVANCE: The findings of this level 3 prospective study provide clinicians working with overhead athletes information regarding shoulder MSI risk and pain. It is recommended that clinicians should not use ROM adaptations exclusively to determine increased risk of shoulder MSI.

Obesity dominates early effects on cardiac structure and arterial stiffness in people with type 2 diabetes.

OBJECTIVE: Type 2 diabetes (T2D) and obesity are global epidemics leading to excess cardiovascular disease (CVD). This study investigates standard and novel cardiac MRI parameters to detect subclinical cardiac and central vascular dysfunction in inactive people with and without T2D. METHODS: Physically inactive age and BMI-similar premenopausal women and men with ( n  = 22) and without [ n  = 34, controls with overweight/obesity (CWO)] uncomplicated T2D were compared to an age-similar and sex-similar reference control cohort ( n  = 20). Left ventricular (LV) structure, function, and aortic stiffness were assessed by MRI. Global arterial pulse wave velocity (PWV) was assessed using carotid-to-femoral applanation tonometry. Regional PWV was measured via 2D phase-contrast MRI and 4D flow MRI. RESULTS: Global arterial PWV did not differ between CWO and T2D. 2D PC-MRI PWV in the ascending aorta was higher in people with T2D compared with CWOs ( P  < 0.01). 4D flow PWV in the thoracic aorta was higher in CWO ( P  < 0.01), and T2D ( P  < 0.001) compared with RC. End-diastolic volume, end-systolic volume, stroke volume, and cardiac output were lower in CWO and T2D groups compared with reference control. CONCLUSION: Subclinical changes in arterial stiffening and cardiac remodeling in inactive CWO and T2D compared with reference control support obesity and/or physical inactivity as determinants of incipient CVD complications in uncomplicated T2D. Future studies should determine the mechanistic causes of the CVD complications in greater detail in order to create therapeutic targets. CLINICAL TRIAL REGISTRATION: Cardiovascular Mechanisms of Exercise Intolerance in Diabetes and the Role of Sex (NCT03419195).

Sex Differences in Physical Activity Among Individuals With Type 2 Diabetes Across the Life Span: A Systematic Review and Meta-analysis.

BACKGROUND: Physical activity (PA) is a cornerstone of type 2 diabetes mellitus (T2DM) treatment. Sex differences in PA behavior or barriers/facilitators to PA among individuals with T2DM are unclear. PURPOSE: To summarize the evidence related to sex differences in participation in PA and barriers/facilitators to PA among individuals with T2DM across the life span. DATA SOURCES: Systematic searches (CRD42021254246) were conducted with Ovid MEDLINE, Embase, Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Allied and Complementary Medicine Database (AMED), APA PsychInfo, and SPORTDiscus. STUDY SELECTION: We included studies with assessment of PA, sedentary behaviors (SB), or barriers/facilitators to PA among individuals with T2DM by sex or gender. DATA EXTRACTION: Participant characteristics, meeting PA guidelines, participation in PA and SB, and barriers/facilitators to PA were extracted by two independent reviewers. DATA SYNTHESIS: A total of 53 articles (65,344 participants) were included in the systematic review and 21 articles in the meta-analysis. Sex differences were not observed in meeting of PA guidelines among adolescents (odds ratio 0.70 [95% CI 0.31, 1.59]), but males were more likely than females to meet PA guidelines among adults (1.65 [1.36, 2.01]) and older adults (1.63 [1.27, 2.09]). Males performed more moderate-to-vigorous PA (MVPA) than females across all age-groups. Common barriers to PA were lack of time (men) and lack of social support and motivation (women). LIMITATIONS: Limitations include heterogeneity of measures used to assess PA and lack of stratification of data by sex. CONCLUSIONS: Sex differences in meeting PA guidelines were not observed among adolescents but were apparent among adults and older adults with T2DM. Females consistently engaged in less MVPA than males across the life span.

Single-leg exercise training augments in vivo skeletal muscle oxidative flux and vascular content and function in adults with type 2 diabetes.

KEY POINTS: People with type 2 diabetes (T2D) have impaired skeletal muscle oxidative flux due to limited oxygen delivery. In the current study, this impairment in oxidative flux in people with T2D was abrogated with a single-leg exercise training protocol. Additionally, single-leg exercise training increased skeletal muscle CD31 content, calf blood flow and state 4 mitochondrial respiration in all participants. ABSTRACT: Cardiorespiratory fitness is impaired in type 2 diabetes (T2D), conferring significant cardiovascular risk in this population; interventions are needed. Previously, we reported that a T2D-associated decrement in skeletal muscle oxidative flux is ameliorated with acute use of supplemental oxygen, suggesting that skeletal muscle oxygenation is rate-limiting to in vivo mitochondrial oxidative flux during exercise in T2D. We hypothesized that single-leg exercise training (SLET) would improve the T2D-specific impairment in in vivo mitochondrial oxidative flux during exercise. Adults with (n = 19) and without T2D (n = 22) with similar body mass indexes and levels of physical activity participated in two weeks of SLET. Following SLET, in vivo oxidative flux measured by 31 P-MRS increased in participants with T2D, but not people without T2D, measured by the increase in initial phosphocreatine synthesis (P = 0.0455 for the group × exercise interaction) and maximum rate of oxidative ATP synthesis (P = 0.0286 for the interaction). Additionally, oxidative phosphorylation increased in all participants with SLET (P = 0.0209). After SLET, there was no effect of supplemental oxygen on any of the in vivo oxidative flux measurements in either group (P > 0.02), consistent with resolution of the T2D-associated oxygen limitation previously observed at baseline in subjects with T2D. State 4 mitochondrial respiration also improved in muscle fibres ex vivo. Skeletal muscle vasculature content and calf blood flow increased in all participants with SLET (P < 0.0040); oxygen extraction in the calf increased only in T2D (P = 0.0461). SLET resolves the T2D-associated impairment of skeletal muscle in vivo mitochondrial oxidative flux potentially through improved effective blood flow/oxygen delivery.

Sitagliptin improves diastolic cardiac function but not cardiorespiratory fitness in adults with type 2 diabetes.

BACKGROUND: People with type 2 diabetes mellitus (T2D) have preclinical cardiac and vascular dysfunction associated with low cardiorespiratory fitness (CRF). This is especially concerning because CRF is a powerful predictor of cardiovascular mortality, a primary issue in T2D management. Glucagon-like pepetide-1 (GLP-1) augments cardiovascular function and our previous data in rodents demonstrate that potentiating the GLP-1 signal with a dipeptidyl peptidase-4 (DPP4) inhibitor augments CRF. Lacking are pharmacological treatments which can target T2D-specific physiological barriers to exercise to potentially permit adaptations necessary to improve CRF and thereby health outcomes in people with T2D. We therefore hypothesized that administration of a DPP4-inhibitor (sitagliptin) would improve CRF in adults with T2D. METHODS AND RESULTS: Thirty-eight participants (64 ±â€¯1 years; mean ±â€¯SE) with T2D were randomized in a double-blinded study to receive 100 mg/day sitagliptin, 2 mg/day glimepiride, or placebo for 3 months after baseline measurements. Fasting glucose decreased with both glimepiride and sitagliptin compared with placebo (P = 0.002). CRF did not change in any group (Placebo: Pre: 15.4 ±â€¯0.9 vs. Post: 16.1 ±â€¯1.1 ml/kg/min vs. Glimepiride: 18.5 ±â€¯1.0 vs. 17.7 ±â€¯1.2 ml/kg/min vs. Sitagliptin: 19.1 ±â€¯1.2 vs. 18.3 ±â€¯1.1 ml/kg/min; P = 0.3). Sitagliptin improved measures of cardiac diastolic function, however, measures of vascular function did not change with any treatment. CONCLUSIONS: Three months of sitagliptin improved diastolic cardiac function, however, CRF did not change. These data suggest that targeting the physiological contributors to CRF with sitagliptin alone is not an adequate strategy to improve CRF in people with T2D. CLINICAL TRIALS REGISTRATION: www.clinicaltrials.gov NCT01951339.

Relationship of performance on the sensory organization test to landing characteristics.

Jump landing tasks have been used to assess landing characteristics and require significant sensorimotor feedback to maintain functional joint stability (FJS) throughout the task. Postural stability (PS) also requires significant sensorimotor feedback and control and would seemingly involve similar sensory feedback pathways. However, previous literature clarifying the relationship between these two processes, maintaining FJS and PS, is limited. 80 Special Tactics Operators. PS was assessed using the Sensory Organization Test (SOT). SOT variables included: Composite, Somatosensory, Visual, Vestibular, and Preference scores. Landing characteristics were assessed using motion analysis during a double-legged (DLSJ) and single-legged (SLSJ) stop jump task. Pearson's correlation coefficients were calculated to assess the relationship between SOT scores and landing characteristics (α < .05). For the DLSJ, significant correlations were found between: Composite and peak posterior ground reaction forces (-.257), Vestibular and peak knee abduction moment (-.237), and Preference and initial contact hip flexion (-.297), peak hip flexion (-.249). For the SLSJ, significant correlations were found between: Somatosensory and peak vertical ground reaction forces (-.246); Preference and initial contact hip flexion (-.295), peak hip flexion (-.262). The results indicate that the SOT may not be a sensitive enough tool to assess sensorimotor control in a healthy, athletic population.

Landing Kinematics and Kinetics at the Knee During Different Landing Tasks.

CONTEXT: Several tasks have been used to examine landing biomechanics for evaluation and rehabilitation, especially as related to anterior cruciate ligament injuries. However, comparing results among studies in which different tasks were used can be difficult, and it is unclear which task may be most appropriate. OBJECTIVE: To compare lower extremity biomechanics across 5 commonly used landing tasks. DESIGN: Descriptive laboratory study. SETTING: University-operated US Air Force Special Operations Forces human performance research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 65 US Air Force Special Tactics Operators (age = 27.7 ± 5.0 years, height = 176.5 ± 5.7 cm, mass = 83.1 ± 9.1 kg). INTERVENTION(S): Kinematic and kinetic analysis of double- and single-legged drop landing, double- and single-legged stop jump, and forward jump to single-legged landing. MAIN OUTCOME MEASURE(S): Hip-, knee-, and ankle-joint kinematics; knee-joint forces and moments; and ground reaction forces (GRFs) were the dependent measures. We used repeated-measures analyses of variance or Friedman tests, as appropriate, to assess within-subject differences across tasks. RESULTS: Peak vertical GRF and peak knee-flexion angle were different among all tasks ( P < .001). Single-legged landings generated higher vertical GRF (χ2 = 244.68, P < .001) and lower peak knee-flexion values ( F4,64 = 209.33, P < .001) except for forward jump to single-legged landing, which had the second highest peak vertical GRF and the lowest peak knee-flexion value. The single-legged drop landing generated the highest vertical (χ2 = 244.68, P < .001) and posterior (χ2 = 164.46, P < .001) GRFs. Peak knee-valgus moment was higher during the double-legged drop landing (χ2 = 239.63, P < .001) but similar for all others. CONCLUSIONS: Different landing tasks elicited different biomechanical responses; no single task was best for assessing a wide range of biomechanical variables related to anterior cruciate ligament injuries. Therefore, depending on the goals of the study, using multiple assessment tasks should be considered.

Military personnel with self-reported ankle injuries do not demonstrate deficits in dynamic postural stability or landing kinematics.

BACKGROUND: The odds of sustaining non-contact musculoskeletal injuries are higher in Special Operations Forces operators than in infantry soldiers. The ankle is one of the most commonly injured joints, and once injured can put individuals at risk for reinjury. The purpose of this study was to determine if any differences in postural stability and landing kinematics exist between operators with a self-reported ankle injury in the past one year and uninjured controls. METHODS: A total of 55 Special Operations Forces operators were included in this analysis. Comparisons were made between operators with a self-reported ankle injury within one-year of their test date (n=11) and healthy matched controls (n=44). Comparisons were also made between injured and uninjured limbs within the injured group. Dynamic postural stability and landing kinematics at the ankle, knee, and hip were assessed during a single-leg jump-landing task. Comparisons were made between groups with independent t-tests and within the injured group between limbs using paired t-tests. FINDINGS: There were no significant differences in dynamic postural stability index or landing kinematics between the injured and uninjured groups. Anterior-posterior stability index was significantly higher on the uninjured limb compared to the injured limb within the injured group (P=0.02). INTERPRETATION: Single ankle injuries sustained by operators may not lead to deficits in dynamic postural stability. Dynamic postural stability index and landing kinematics within one year after injury were either not affected by the injuries reported, or injured operators were trained back to baseline measures through rehabilitation and daily activity.