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THE EFFECT OF ARM SWINGS ON LOWER LIMB KINETICS DURING SINGLE-LEG HOPPING
No full textSingle-leg forward hopping for distance was widely used to evaluate knee functions and quadriceps strength following anterior cruciate ligament (ACL) injuries. Single-leg vertical hopping for height and backward hopping for distance were found to require more knee involvement compared to forward hopping. There is a lack of consistent task instruction for performing hopping tasks to sensitively monitor knee function following ACL injuries. PURPOSE: To quantify the effects of arm swings on lower limb kinetics during single-leg forward, vertical, and backward hopping with a focus on knee assessment. METHODS: 38 injury-free individuals (21.0 ± 2.3 yrs, 1.7 ± 0.1 m, 68.6 ± 12.9 kg) performed single-leg forward (FH), vertical (VH), and backward (BH) hopping with and without arm swings with motion and force data collected during jumping. Hopping performance, hip/knee/ankle work, and peak power were calculated and compared by three-by-two repeated-measures ANOVAs. RESULTS: BH showed the greatest peak knee power (p \u3c 0.001), smallest hip/ankle work (p \u3c 0.001), and smallest hip/ankle peak power (p \u3c 0.001) compared to FH and VH, regardless of arm swings (Table 1). Arm swings significantly increased hopping performance (p \u3c 0.001) among all tasks but decreased knee work (p = 0.004) in VH and BH (Table 1). CONCLUSION: The greatest peak knee power and smallest peak hip/ankle power and work in BH support the greater emphasis of the knee when hopping backward. Therefore, BH might be an additional task to assess the knee function following ACL injuries compared to FH and VH. Arm swings resulted in greater performance without significantly increasing knee emphasis during jumping. Standardized instructions on controlling arms are recommended when using performances from hopping tasks to assess knee function in rehabilitation progress in patients after ACL injuries. Future studies need to investigate the knee kinetics when hopping in different directions in patients after ACL injuries. Table1. Mean ± standard deviation of performance, peak hip/knee/ankle power, and hip/knee/ankle work with and without arm swings during single-leg forward, vertical, and backward hopping
THE EFFECT OF LEUCINE SUPPLEMENTATION ON ATROGENES IN AGED MALE MICE AT THE ONSET OF MUSCLE REGENERATION.
No full textINTRODUCTION: Skeletal muscle regeneration is a crucial biological process that restores muscle tissue following injury. However, aging significantly diminishes the capacity for muscle repair, leading to delayed recovery in older individuals. This diminished regenerative capacity is associated with dysregulated protein turnover, characterized by increased expression of genes associated with protein degradation, called atrogenes. Leucine, a branched-chain amino acid, has shown promise in altering protein turnover. Previous work by our group demonstrated that independent of leucine supplementation, injury-induced atrogene expression in female mice. PURPOSE: To investigate the effects of leucine supplementation on gene expression of atrogenes in aged male mice at the onset of muscle regeneration. METHODS: Experiments were conducted exclusively on aged male C57/BL6 mice (24 months old), which were divided into four groups: uninjured without leucine (UNL), uninjured with leucine (UL), injured without leucine (INL), and injured with leucine (IL). Muscle injury was induced in the tibialis anterior (TA) muscles using bupivacaine injections, while uninjured groups received phosphate-buffered saline (PBS). Leucine supplementation (1.5%) was administered ad libitum via drinking water. TA muscles were harvested three days post-injection, and quantitative PCR was performed to assess gene expression changes. Data was analyzed by two-way ANOVA and significance was established at (p \u3e 0.05). RESULTS: There were no differences in body mass between UNL, INL, UL, and IL (P\u3e0.05). There was no difference in the TA mass across the 4 groups (46.2 mg ± 2.6, 51.7 mg ± 1.7, 51.5 mg ± 1.2, 49.2 mg ± 1.0) (P\u3e0.05). There were no fold differences in atrogenes mRNA abundance of atrogenes Foxo3, Foxo1, Atrogin, and Murf1 (P\u3e0.05). CONCLUSION: Leucine was not sufficient to alter atrogene expression at the onset of muscle regeneration in male mice. In contrast to our published data in female mice, male mice did not increase atrogene expression in response to injury. This could partially explain the biological sex differences seen during aged skeletal muscle regeneration
THREE NEUROCOGNITIVE MOBILE APPLICATIONS: PERCEPTION OF USABILITY IN ADULTS WITH AND WITHOUT PARKINSON’S DISEASE
No full textMobile technology and applications are now commonly used for neurocognitive testing. Adequate motor control is necessary to perform such assessments. PURPOSE: This study assessed the perceived usability of three neurocognitive mobile applications among healthy individuals and those with Parkinson’s Disease (PD). METHODS: 25 adults (10 females, 15 males), aged 57 to 81 years, divided into two groups: (1) without PD (n= 11; m= 70.36 ± sd= 6.87yrs) and (2) with PD (n= 14; m= 72.64 ± sd= 4.55yrs). Participants completed three trials (initial, wk2, wk4) on three neurocognitive mobile applications (NMA) (app1-smartphone, app2-tablet, app3-touchscreen monitor). Following each trial, perceived level of difficulty (PLD) per NMA was recorded, and NMA preference ranked. Two separate 3x3x2 repeated measures ANOVAs were administered. First, PLD of NMA across trials between groups, and the second to determine preference of NMA. RESULTS: Greenhouse-Geisser on PLD reported a significant main effect for NMA, F(1.501, 16) = 6.354, p= 0.01, ηp² = 0.28, power = 0.79. No other interactions or main effects for PLD of NMA across trials between groups were found to be significant (p\u3c 0.05). Post-hoc PLD tests revealed both the app1-smartphone (p= 0.01) and app2-tablet (p= 0.02) were significantly easier to use than app3-touchscreen monitor for non-PD. Greenhouse-Geisser also determined preference rankings of the three NMA across trials between groups showing a significant main effect of the NMA, F(1.966, 16) = 14.884, p \u3c 0.001, ηp² = 0.48, power = 0.99. All other analyses showed no significant interactions or main effects (p\u3c 0.05). Post-hoc tests revealed app1-smartphone was the most preferred NMA irrespective of PD status followed by app2-table, and app3-touchscreen being the least preferred. CONCLUSION: Findings suggest, smartphones and tablets were generally perceived as easier to use than touchscreen monitors for neurocognitive assessments, regardless of PD status. Furthermore, participants consistently favored the smaller smartphone and app followed by the tablet-driven app, with the larger touchscreen monitor and app being least preferred. These findings highlight the importance of considering motor control challenges, especially for individuals with PD, when selecting devices for neurocognitive testing
Bioimpedance Minimally Improves Prediction of Bone Mineral Density Beyond Demographic Information Alone
Get PDFBone mineral content (BMC) serves as an important indicator of osteoporosis risk. Traditional methods of BMC estimation include using demographic information within prediction equations, which draw from population trends but may not reflect individual variance in BMC. Dual-energy X-ray absorptiometry (DXA) provides a more accurate assessment of BMC but may pose challenges in clinical settings due to certification requirements, cost, and space requirements. Bioelectrical impedance analysis (BIA) has shown promise in correlating with BMC and may offer an intriguing alternative due to its accessibility, but its efficacy compared to traditional methods remains largely unexplored. PURPOSE: Quantify the contribution of BIA assessment on accuracy of BMC estimations compared to the traditional demographic information alone. METHODS: Three-hundred and twelve adults (n=193 F, n=119 M; [mean ± SD] age: 30.2 ± 13.0 y; body mass: 71.2 ± 14.7 kg; height: 169.6 ± 9.1 cm; body fat: 27.8 ± 8.7%) completed DXA and standing multi-frequency bioelectrical impedance analysis (MFBIA) assessments in a single laboratory visit. Two multiple linear regression models were fit to predict DXA BMC. The demographic model included age, sex, weight, and height as predictors, while the demographic + bioimpedance model additionally included total body bioelectrical resistance at the 50 kHz frequency. Regression model performance was quantified by the R2, root mean square error (RMSE), and Akaike information criterion (AIC). RESULTS: In both models, weight, height and the male sex were positively related to BMC, while age was negatively related to BMC (p\u3c0.01 for all). Although bioelectrical resistance was negatively related to DXA BMC (p\u3c0.01), it exerted a minimal improvement in the overall regression model performance (demographic model: R2: 0.79, RMSE: 241 g, AIC: 4321; demographic + bioimpedance model: R2: 0.82, RMSE: 225 g, AIC: 4280). CONCLUSIONS: The inclusion of bioelectrical impedance analysis (BIA) resulted in only a modest improvement in model performance compared to the demographic model. These findings suggest that BIA-derived BMC estimations may not provide clinically significant benefit, nor should the BMC estimation provided by BIA hold substantially greater weight in the minds of clinicians and patients alike. Though this study did not indicate the need for widespread implementation of BIA-derived BMC assessments, further experimentation involving a more diverse population, particularly for those at greater risk of osteoporosis, could offer valuable insight into the potential of BIA in accurate monitoring and detection
Targeted Soleus Muscle Activation Enhances Very Low-Density Lipoprotein Triglyceride Metabolism via Lipoprotein Lipase
Get PDFLipoprotein lipase (LPL) is the rate limiting enzyme for tissue specific plasma triglyceride (TG) utilization. There is a strong causal link between LPL and cardiovascular health. PURPOSE: Our translational studies investigated the soleus muscle aiming to answer the following questions: What are the mechanisms responsible for the potent process of regulating LPL within the soleus muscle? Can individuals with low fitness levels capitalize on the unique phenotype of the soleus muscle to markedly enhance systemic plasma lipid metabolism through localized contractile activity, even though the muscle constitutes only ~1% of body weight? METHODS: We began by testing the hypothesis that LPL is stimulated by ambulatory activity because of a mechanism involving tissue specific LPL binding to the soleus vasculature, but not in other tissues. 125I-LPL was injected into the left jugular vein to compare relatively inactive vs active rats. Next, we developed a feasible method of isolated plantarflexion in seated humans to determine if targeting the soleus would be sufficient to cause large improvements in lipid metabolism. RESULTS: In rats, there was a strong correlation between endogenous LPL activity and the binding of radiolabeled 125I-LPL (R² = 0.86; P \u3c 0.0001), with activity rapidly increasing binding affinity to the soleus endothelium (~2-fold, P \u3c 0.001), a response absent in less oxidative muscles. In humans, we developed a low-effort seated activity to engage the soleus muscle without causing fatigue or adverse effects, even after prolonged sessions (~5 hours; N = 35). Among 7 participants undergoing invasive tests, this specific activation of soleus lipid metabolism reduced very low-density lipoprotein triglycerides (VLDL-TG) to 73 ± 5% of baseline. CONCLUSION: Sedentary time is increasingly prevalent worldwide, leading to a number of rapidly deleterious effects. Utilizing the fatigue resistant oxidative soleus muscle during seated behaviors provides a potent method of increasing catabolism of VLDL-TG. In addition to providing a method of improving the blood lipid profile, these findings also show that a small muscle can have profound whole-body effects
The Impact of Big Steps Obstacle Negotiation on Knee Extensor Control, Hip Abductor Activation, and Inter-joint Coordination: A Potential Rehabilitation Strategy
Get PDFNavigating obstacles while walking is a critical daily activity that requires both precise coordination and balance control, which has significant implications for fall prevention and rehabilitation. PURPOSE: This study aimed to investigate the biomechanical and neuromuscular mechanisms that underlie balance strategies during normal and big step obstacle crossing. METHODS: Twelve healthy young adults (ages 20–24) performed leap-style crossovers of a 15 cm (5.90”) high, 45° angled obstacle under two conditions: normal and big steps. Participants ensured their dominant leg landed on a force plate, entering the single-limb support (SLS) phase for analysis. One-way repeated ANOVA was used for each variable to compare between the big step and normal step. RESULTS: Big steps required a significantly greater knee flexion angle (36.36° ± 18.82° vs. 27.10° ± 16.20°, p \u3c 0.05), eccentric knee extensor power (18.70 ± 6.20 W/kg vs. 15.60 ± 6.94 W/kg, p \u3c 0.05), and eccentric work (3.16 ± 3.27 J/kg vs. 1.99 ± 1.25 J/kg, p \u3c 0.05). Joint coordination was less synchronized during big steps and had a longer lag for the relationship between the ankle and knee (0.13 ± 0.18 s vs. 0.05 ± 0.02 s, p \u3c 0.05) as well as the knee and hip (0.28 ± 0.25 s vs. 0.17 ± 0.18 s, p \u3c 0.05). Additionally, knee-hip movements were opposite in direction for big steps (knee forward, hip backward), this contrasted from the synchronized forward movement observed in normal steps. Relative muscle contributions increased significantly in big steps, with greater activation of the quadriceps (21.37% ± 7.13% vs. 17.61% ± 6.08%, p \u3c 0.05) and gluteus medius (11.04% ± 3.77% vs. 9.50% ± 3.05%, p \u3c 0.05). CONCLUSION: These findings emphasize the heightened stabilization demands required by big steps during obstacle crossing. The greater knee flexion and increased eccentric power and work suggest a stronger reliance on the knee extensors for shock absorption and balance recovery. Meanwhile, the reduced joint synchronization and the opposite knee-hip movement patterns highlight the challenge of maintaining dynamic stability during big steps. Increased activation of the gluteus medius during the big step had a critical role in hip stabilization, compensating for the reduced coordination between the knee and hip joints. These findings strongly support the inclusion of big step training in rehabilitation programs aimed at improving lower extremity function. By specifically targeting knee extensor eccentric control, hip abductor strength, and inter-joint coordination, rehabilitation can enhance functional mobility and reduce the risk of falls
Music Enhances Motor Cortex Excitability in Physically Active Individuals
Get PDFMusic is often used by exercisers and benefits physical performance. The positive effects of music on physical function are induced by the changes in motor cortex excitability while listening to music. Recent studies reveal that modulation of brain excitability in the hand is increased by music but is likely dependent on the characteristics of music tempo, preference, and the individual’s motivational state. No study has explicitly investigated whether music perceived as motivating for exercise creates changes in motor cortex excitability of the quadriceps. PURPOSE: This randomized crossover study examines the effect of the preferred music on motor cortex excitability of the quadriceps in physically active individuals. METHODS: Eleven physically active participants (age: 21.2 ± 1.5 years, weight: 61.8 ± 12.6 kg, and height: 160.9 ± 10.1 cm) were assigned to both preferred music condition (PM; music they preferred to exercise to) and non-preferred music (NPM; curated music of tempo ≤ 120 beats per minute [bpm] aimed at inducing relaxation) on separate days in random order. Transcranial Magnetic Stimulation (TMS) was used to measure the motor evoked potential (MEP) of the rectus femoris as a neurophysiological marker of motor cortex excitability at 110%, and 120% of the Resting Motor Threshold (RMT). To assess the perception of motivation for the musical pieces used in PM and NPM, the Brunnel Music Rating Inventory (BMRI-2) was completed after each condition. A 2x3 repeated-measures analysis of variance (ANOVA) was conducted with each music conditions (PM and NPM) and three time points (before, during, and after listening to music) to determine the effects of PM on motor cortex excitability at two separate TMS intensities. Post-hoc tests with Sidak adjustments were performed when necessary. A paired t-test was used to compare BMRI-2 scores between PM and NPM. The significance level was set at ≤ 0.05. RESULTS: There were no significant condition x time interaction effects at either RMT intensity (p \u3e 0.05). However, significant differences were observed in MEP across the three time points for both TMS intensities (pp = 0.036) and decreased after music listening (p = 0.004) from baseline. At 120% of RMT, MEP increased during music listening (p = 0.028) and remained elevated after music listening (p = 0.029) compared to baseline. A paired t-test revealed significantly higher motivational factors in PM (39.54 ± 3.5) compared to NPM (17.9 ± 6.9; p \u3c .001). CONCLUSION: Music, regardless of preference, enhances the motor cortical excitability. While PM was perceived as more motivational for exercise than NPM, this did not significantly affect motor cortex excitability. It was observed that the tempo of PM was lower than anticipated (112.6 ± 13.26bpm), which may explain the lack of significant differences between the two conditions. These findings suggest that while musical preference and motivational perception are of interest psychologically, the tempo of the music may play a more critical role in modulating motor cortex excitability of the quadriceps. Future studies on the role of tempo in brain excitability are warranted
Muscle Metabolic Profile Following Acute Exercise in Mice with Constitutively Active mTORC1
Get PDFAn increase in Mechanistic Target of Rapamycin Complex I (mTORC1) kinase activity stimulates muscle protein synthesis in response to amino acids, growth factors, energy, and mechanical stimuli. We previously found muscle hypertrophy and increased mitochondrial respiration in resting mice with chronically active mTORC1 (i.e., an inducible skeletal muscle specific DEPDC5 knockout (KO) model), but no improvement in muscle quality and function. PURPOSE: The purpose of this study was to determine the metabolic profile of skeletal muscle in DEPDC5 KO and wild-type (WT) male and female mice following 1-hour of treadmill exercise. METHODS: Targeted metabolomics was performed on quadricep muscle, with a total of 272 polar metabolites being detected. RESULTS: Acute exercise induced a differential response in metabolites related to fuel utilization, amino acid metabolism, and nucleotide metabolism between mice with hyperactive mTORC1 and wild-type control mice. Genotype had a much stronger impact than exercise, with predominantly decreased metabolites in sedentary mice that were partially restored with exercise. CONCLUSION: We conclude that increased mTORC1 signaling modifies the skeletal muscle metabolome in response to exercise, indicating that mTORC1 signaling plays a key role in regulating muscle metabolism. Understanding these mechanisms could lead to the development of strategies for restoring mTORC1 signaling in conditions associated with chronically active mTORC1 signaling such as aging and cancer
Correlating Visuomotor and Cognitive Assessments to Marksmanship in Police Cadets
Get PDFTests such as the Eriksen Flanker Task, and the Cue and Go test are commonly used to directly measure police cadet cognitive performance. A light board task is a type of cognitive task that typically involves the use of a visual board, often illuminated, to assess or stimulate cognitive processes such as attention, perception, memory, and executive functioning. There is little to no information about comparisons made between lightboard cognitive performance and marksmanship accuracy within the police cadet population. PURPOSE: Evaluate the correlations found between lightboard cognitive tasks (Tactical 1, Tactical 2) and police cadet marksmanship scores. METHODS: 12 police cadets (n = 4 female; n = 8 male) participated in both cognitive lightboard task and a standard marksmanship test. Marksmanship data was collected via academy firearms qualification testing and scores were based on the proximity to the center of the target. Lightboard data was collected via the Dynavision D2 machine, with tests (Tactical 1, Tactical 2) being designed to measure cognitive performance under stimulated stress. Tactical 1&2 involved decision making and performance under more complex conditions. A Pearson’s r correlation was used to analyze the relationship between marksmanship total score and light board “total hit scores. RESULTS: Overall marksmanship scores had a statically significant strong positive correlation with tactical 1 total hits (r = 0.687, p = 0.007), and a statistically significant, moderately strong positive correlation with tactical 2 total hits (r = 0.520, p = 0.041). CONCLUSION: Lightboard cognitive scores may have a predictive property to marksmanship scores. Further research could facilitate using lightboard cognitive testing for visuomotor deficiency detection for marksmanship performance, along with supporting potential intervention strategies
Angiotensin II Induced Hypertension Induces DNA Damage Associated Gene Expression in Visceral Adipose
Get PDFAdvanced age remains the most important risk factor for the development of cardiovascular disease. Aging is also the major risk factor for hypertension and is associated with chronic inflammation and senescent cell accumulation. Cellular senescence, a state of irreversible cell cycle arrest, is characterized by cell cycle arrest and the secretion of inflammatory mediators known as the senescence-associated secretory phenotype (SASP). Senescent cells have been demonstrated to accumulate in the adipose tissue of old mice. Although cellular senescence plays a role in age-related vascular dysfunction, it is unknown whether hypertension can induce cellular senescence independent of age. PURPOSE: This study aims to determine whether Angiotensin (Ang) II-induced hypertension results in cellular senescence and SASP-related gene expression in visceral adipose tissue (VAT) mice. METHODS: C57BL/6 mice of both sexes, aged 4-6 months, were divided into two groups: an Ang II-treated group, which received Ang II (500 ng/kg/min) via subcutaneous osmotic pumps for 14 days (a protocol shown to induce hypertension), and a sham-treated group, which received vehicle solution under the same conditions. Using qPCR, we assessed genes that are associated with senescence Cdkn2a(p16), Cdkn1a (p21), and Trp53 (p53) and SASP associated inflammatory genes Interleukin-6 (Il6), Tumor-necrosis factor-α (Tnfa), interferon-γ (Ifng), CCL2 (Ccl2), and CCL5 (Ccl5) in the VAT using the ΔΔct method. Group Differences were assessed by unpaired t-test. Data are normalized to control group and are mean ± SEM. RESULTS: While the Ang II-treated group exhibited a significant increase in p53 expression, a marker of DNA damage (p = 0.04), there was no difference in the relative gene expression of p16 and p21 between the Ang II-treated and control groups (p = 0.43, p=0.14). Similarly, no significant differences were found in the relative gene expression of Il6, Tnfa, Ifng, Ccl2, and Ccl5 (p = 0.09, p = 0.09, p = 0.12, p=0.14 and p = 0.47, respectively). CONCLUSION: Our data suggests that Ang II induced hypertension may result in greater DNA damage (p53) a precursor to senescence/SASP. However, hypertension alone may not be sufficient to induce overall senescence and SASP