Isometric Knee Extension Force Research Articles

Comparison of force and timing control in periodic isometric leg extension

BackgroundIn daily life and sports activities, the regulation of muscle force and timing is often not controlled independently, rather the appropriate amount of force is controlled simultaneously with appropriate timing. However, which of the two variables, force or timing, is more difficult to control remains unclear. ObjectiveWe aimed to investigate the difficulty in the accurate control of force and timing, simultaneously. By setting target levels for force and timing interval, with both target lines presented, none of them presented, or only one of the target lines for force or timing interval presented, we directly examined and identified which variable is more important. MethodsParticipants were asked to produce periodic isometric knee extension force using their right leg. The following four tasks were established: 20 %MVF-1000 ms task (20 % maximum voluntary force [MVF] at 1000 ms intervals), 20 %MVF-2000 ms task (20 % MVF at 2000 ms intervals), 40 %MVF-1000 ms task (40 % MVF at 1000 ms intervals), and 40 %MVF-2000 ms task (40 % MVF at 2000 ms intervals). Moreover, the participants performed four tasks under the following four conditions based on target line presentation: Both variables condition (force and interval lines presented), force condition (only force line presented), interval condition (only interval line presented), and no variable condition (neither force nor interval lines presented). The recorded force data were analyzed. ResultsRegarding the force factor, the error of the interval and no variable conditions was greater than that of the both variables and force conditions. As for the interval factor, the error was greater when the target interval line was not presented (force and no variable conditions) than when it was presented (both variables and interval conditions), and it exceeded the target interval in the 1000 ms task, whereas it was shorter than the target interval in the 2000 ms task. Except for the force condition, the force factor showed significantly greater absolute errors when the target level was set as 100 %, compared to the interval factor. ConclusionsThe control of force was found to be more difficult than that of timing, based on aspects relating to accuracy and reproducibility.

Effects of a home-based, exergaming intervention on physical function and pain after total knee replacement in older adults: a randomised controlled trial

ObjectivesTo investigate the effects of 4 months of customised, home-based exergaming on physical function and pain after total knee replacement (TKR) compared with standard exercise protocol.MethodsIn this non-blinded randomised controlled...

Muscle mass, quality, and strength; physical function and activity; and metabolic status in cachectic patients with head and neck cancer

Cancer cachexia is commonly associated with poor prognosis in patients with head and neck cancer (HNC). However, its pathophysiology and treatment are not well established. The current study aimed to assess the muscle mass/quality/strength, physical function and activity, resting energy expenditure (REE), and respiratory quotient (RQ) in cachectic patients with HNC. This prospective cross-sectional study analyzed 64 patients with HNC. Body composition was measured via direct segmental multifrequency bioelectrical impedance analysis, and muscle quality was assessed using echo intensity on ultrasonography images. Muscle strength was investigated utilizing handgrip strength and isometric knee extension force (IKEF). Physical function was evaluated using the 10-m walking speed test and the five times sit-to-stand (5-STS) test. Physical activity was examined using a wearable triaxial accelerometer. REE and RQ were measured via indirect calorimetry. These parameters were compared between the cachectic and noncachectic groups. In total, 23 (36%) patients were diagnosed with cachexia. The cachectic group had a significantly lower muscle mass than the noncachectic group. Nevertheless, there was no significant difference in terms of fat between the two groups. The cachectic group had a higher quadriceps echo intensity and a lower handgrip strength and IKEF than the noncachectic group. Moreover, they had a significantly slower normal and maximum walking speed and 5-STS speed. The number of steps, total activity time, and time of activity (<3 Mets) did not significantly differ between the two groups. The cachectic group had a shorter time of activity (≥3 Mets) than the noncachectic group. Furthermore, the cachectic group had a significantly higher REE/body weight and REE/fat free mass and a significantly lower RQ than the noncachectic group. The cachectic group had a lower muscle mass/quality/strength and physical function and activity and a higher REE than the noncachectic group. Thus, REE and physical activity should be evaluated to determine energy requirements. The RQ was lower in the cachectic group than that in the noncachectic group, indicating changes in energy substrate. Further studies must be conducted to examine effective nutritional and exercise interventions for patients with cancer cachexia.

The physiological, perceptual and neuromuscular responses of team sport athletes to a running and cycling high intensity interval training session

PurposeThe acute physiological, perceptual and neuromuscular responses to volume-matched running and cycling high intensity interval training (HIIT) were studied in team sport athletes.MethodsIn a randomized cross-over design, 11 male team sport players completed 3 × 6 min (with 5 min between sets) repeated efforts of 15 s exercising at 120% speed (sdot{text{V}}O2max) or power (pdot{text{V}}O2max) at dot{text{V}}O2max followed by 15 s passive recovery on a treadmill or cycle ergometer, respectively.ResultsAbsolute mean dot{text{V}}O2 (ES [95% CI] = 1.46 [0.47–2.34], p < 0.001) and heart rate (ES [95% CI] = 1.53 [0.53–2.41], p = 0.001) were higher in running than cycling HIIT. Total time at > 90% dot{text{V}}O2max during the HIIT was higher for running compared to cycling (ES [95% CI] = 1.21 [0.26–2.07], p = 0.015). Overall differential RPE (dRPE) (ES [95% CI] = 0.55 [− 0.32–1.38], p = 0.094) and legs dRPE (ES [95% CI] = − 0.65 [− 1.48–0.23], p = 0.111) were similar, whereas breathing dRPE (ES [95% CI] = 1.01 [0.08–1.85], p = 0.012) was higher for running. Maximal isometric knee extension force was unchanged after running (ES [95% CI] = − 0.04 [− 0.80–0.8], p = 0.726) compared to a moderate reduction after cycling (ES [95% CI] = − 1.17 [− 2.02–0.22], p = 0.001).ConclusionCycling HIIT in team sport athletes is unlikely to meet the requirements for improving run-specific metabolic adaptation but might offer a greater lower limb neuromuscular load.

Association of phase angle with muscle function and prognosis in patients with head and neck cancer undergoing chemoradiotherapy

ObjectivesThe aims of this study were to investigate the correlation of phase angle (PhA) with other parameters (e.g., muscle mass/quality/strength and physical function), assess the prognostic relevance of prechemoradiotherapy (CRT) PhA, and suggest a reference value of PhA in Asian patients with head and neck cancer (HNC). MethodsNinety-six patients with HNC who underwent CRT were divided into two groups— maintained-PhA group and low-PhA group—according to the PhA 25th percentile values by sex. Pretreatment PhA was measured using direct segmental multifrequency bioelectrical impedance analysis, and muscle quality was assessed using echo intensity in ultrasound images. Correlation of PhA with other parameters was investigated, and between-group differences with respect to adverse events, treatment interruption, and 3-y survival were assessed. ResultsPhA showed a positive correlation with isometric knee extension force (R = 0.710), handgrip strength (R = 0.649), skeletal muscle mass index (R = 0.620), and maximum gait speed (R = 0.543; P < 0.001). PhA showed a negative correlation with echo intensity (R = −0.439) and five times sit-to-stand test (R = −0.505; P < 0.01). The low-PhA group had a higher incidence of severe anemia (52% in low-PhA versus 17% in maintained-PhA), aspiration (17 versus 1%), radiotherapy interruption (17 versus 3%), and poor 3-y survival (47 versus 81%) than the maintained-PhA group (P < 0.05). ConclusionPhA was correlated with muscle mass/quality/strength, and physical function. Low PhA was associated with severe adverse events, treatment interruption, and shorter survival. These findings suggested that 4.6° for men and 4° for women may be useful as prognostic reference values in Asian patients with HNC.

Impact or No Impact for Women With Mild Knee Osteoarthritis: A Bayesian Meta-Analysis of Two Randomized Controlled Trials With Contrasting Interventions.

To predict the probability of a benefit from 2 contrasting exercise programs for women with a new diagnosis of mild knee osteoarthritis, and to estimate the short- and long-term effects of aquatic resistance training (ART) and high-impact aerobic land training (HLT) compared with a control. Original data sets from 2 previously conducted randomized controlled trials were combined and used in a Bayesian meta-analysis. Group differences in multiple response variables were estimated. Variables included cardiorespiratory fitness, dynamic maximum leg muscle power, maximal isometric knee extension and flexion force, pain, other symptoms, and quality of life. The statistical model included a latent commitment variable for each female participant. ART had a 55-71% probability of benefits in the outcome variables, and as the main effect, the intervention outperformed the control in cardiorespiratory fitness, with a probability of 71% immediately after the intervention period. HLT had a 46-63% probability of benefits after intervention with the outcome variables, but differently from ART; the positive effects of physical performance fade away during the follow-up period. Overall, the differences between groups were small, and the variation in the predictions between individuals was high. Both interventions had benefits, but ART has a slightly higher probability of long-term benefits on physical performance. Because of high individual variation and no clear advantage of one training method over the other, personal preferences should be considered in the selection of the exercise program to ensure highest commitment to training.

Association Between Free-Living Sit-to-Stand Transition Characteristics, and Lower-Extremity Performance, Fear of Falling, and Stair Negotiation Difficulties Among Community-Dwelling 75 to 85-Year-Old Adults.

BackgroundGood sit-to-stand (STS) performance is an important factor in maintaining functional independence. This study investigated whether free-living STS transition volume and intensity, assessed by a thigh-worn accelerometer, is associated with characteristics related to functional independence.MethodsFree-living thigh-worn accelerometry was recorded continuously for 3–7 days in a population-based sample of 75-, 80-, and 85-year-old community-dwelling people (479 participants; women n = 287, men n = 192). The records were used to evaluate the number and intensity (angular velocity of the STS phase) of STS transitions. Associations with short physical performance battery (SPPB), 5-times-sit-to-stand test (5×STS), isometric knee extension force, self-reported fear of falls, and self-reported difficulty in negotiating stairs were also assessed.ResultsThe number of STS transitions, mean and maximal angular velocity were lower in older age groups (p < .05). All variables were higher in men than in women (p < .001) and were positively associated with SPPB total points, knee extension force (r ranged from 0.18 to 0.39, all p < .001) and negatively associated with 5×STS (r = −0.13 – −0.24, all p < .05), lower extremity functional limitations (p < .01), fear of falls (p < .01), and stair negotiation difficulties (p < .01).ConclusionsFree-living STS characteristics were related to lower-extremity performance, lower extremity functional limitations, self-reported fear of falls, and stair negotiation difficulties, which can be a sensitive indicator of impending functional decline. Moreover, STS transitions may provide an indicator of adequacy of lower-limb muscle strength among older individuals.

Relative Validity and Reliability of Isometric Lower Extremity Strength Assessment in Older Adults by Using a Handheld Dynamometer.

Handheld dynamometry (HHD) is a practical alternative to traditional testing of lower extremity strength. However, its reliability and validity across different populations and settings are not clear. We hypothesize that HHD is a valid and reliable device to assess lower extremity strength in a population of older adults. Cross-sectional/cohort. Level 3. This study included 258 older adults (≥65 years). Isometric knee extension and flexion force were measured by 1 examiner, using an HHD (n = 222), including 3 repetitions to calculate within-day intrarater reliability. These measurements were repeated by the examiner in a subgroup (n = 23) to analyze intrarater reliability over a test-retest period of on average 8 weeks. In addition, HHD force measures were performed by a second examiner (n = 29) to analyze interrater reliability. In another subgroup (n = 77), isometric knee extension and flexion torque were measured by 1 examiner using both the HHD and Biodex System 4 to assess relative validity. HHD and Biodex measurements were highly correlated and showed excellent concurrent validity. HHD systematically overestimated torque as compared with Biodex by 8 N·m on average. Same-day intrarater intraclass correlation coefficients (ICCs) ranged from 0.97 to 0.98. Interrater reliability ICCs ranged from 0.83 to 0.95. HHD represents a reliable and valid alternative to Biodex to rank individuals on leg strength, or to assess within-person changes in leg strength over time, because of the high validity and reliability. The HHD is less suited for absolute strength assessment because of significant systematic overestimations. Clinicians are encouraged to use HHD to rank older adults on leg strength, or to assess within-person changes in leg strength over time, but not to compare readings with cut-offs or normative values.

Age-related increase in muscle stiffness is muscle length dependent and associated with muscle force in senior females

BackgroundIn aging, muscle stiffness is considered as one of the factors associated with the reduction of force generation capability. There have been inconsistent findings on age-related alteration in the passive stiffness of quadriceps muscle in the female adults. Thus, the aim of this study was to determine the effect of aging on the shear moduli of the superficial muscle heads of the quadriceps and to explore its relationship with knee extension force.MethodsPassive shear moduli of the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) were measured at rest using shear wave elastography in 20 young and 20 senior female adults. Measurements were repeated at four knee joint positions, that is, 30°, 60°, 90°, and 105° of knee flexion. Maximal isometric voluntary knee extension force was assessed at 30°, 60°, and 90° of knee flexion.ResultsAs per our findings, senior adults were determined to have significantly higher passive muscle shear moduli in the RF (by 34% – 68%; all p < 0.05) and the VL muscle heads (by 13%–16%, all p < 0.05) at and beyond 60° of knee flexion. Age-related increase in the VM was evident at 105° knee flexion (by11%, p = 0.020). The RF shear modulus was negatively correlated to the maximal isometric voluntary contraction force measured at 60° (r = − 0.485, p = 0.030) in senior adults.ConclusionsSenior female adults had greater passive stiffness at the superficial muscle heads of the quadriceps muscles when measured at long muscle length. Among the senior female adults, the passive stiffness of RF has been determined to have a negative association with the knee extensor force only at 60° knee flexion. No significant association was noted for other angles and muscles.

Older Compared With Younger Adults Performed 467 Fewer Sit-to-Stand Trials, Accompanied by Small Changes in Muscle Activation and Voluntary Force.

Background: Repetitive sit-to-stand (rSTS) is a fatigue perturbation model to examine the age-effects on adaptability in posture and gait, yet the age-effects on muscle activation during rSTS per se are unclear. We examined the effects of age and exhaustive rSTS on muscle activation magnitude, onset, and duration during ascent and descent phases of the STS task.Methods: Healthy older (n = 12) and younger (n = 11) adults performed rSTS, at a controlled frequency dictated by a metronome (2 s for cycle), to failure or for 30 min. We assessed muscle activation magnitude, onset, and duration of plantar flexors, dorsiflexors, knee flexors, knee extensors, and hip stabilizers during the initial and late stages of rSTS. Before and after rSTS, we measured maximal voluntary isometric knee extension force, and rate of perceived exertion, which was also recorded during rSTS task.Results: Older vs. younger adults generated 35% lower maximum voluntary isometric knee extension force. During the initial stage of rSTS, older vs. younger adults activated the dorsiflexor 60% higher, all 5 muscle groups 37% longer, and the hip stabilizers 80% earlier. Older vs. younger adults completed 467 fewer STS trials and, at failure, their rate of perceived exertion was ~17 of 20 on the Borg scale. At the end of the rSTS, maximum voluntary isometric knee extension force decreased 16% similarly in older and younger, as well as the similar age groups decline in activation of the dorsiflexor and knee extensor muscles (all p < 0.05).Conclusion: By performing 467 fewer STS trials, older adults minimized the potential effects of fatigability on muscle activation, voluntary force, and motor function. Such a sparing effect may explain the minimal changes in gait after rSTS reported in previous studies, suggesting a limited scope of this perturbation model to probe age-effects on muscle adaptation in functional tasks.

The Effect of Resistance Exercise Priming in the Morning on Afternoon Sprint Cross-Country Skiing Performance.

We tested whether a single session of heavy-load resistance priming conducted in the morning improved double-poling (DP) performance in the afternoon. Eight national-level male cross-country skiers (mean [SD]: 23 [3]y, 184 [6]cm, 73 [7]kg, maximum oxygen consumption = 69 [6]mL·kg-1·min-1) carried out 2days of afternoon performance tests. In the morning, 5hours before tests, subjects were counterbalanced to either a session of 3 × 3 repetitions (approximately 85%-90% 1-repetition maximum) of squat and sitting pullover exercises or no exercise. The performance was evaluated in DP as time to exhaustion (TTE) (approximately 3min) on a treadmill and 30-m indoor sprints before and after TTE (30-m DP pre/post). Furthermore, submaximal DP oxygen cost, countermovement jump, and isometric knee-extension force during electrical stimulation were conducted. Participants reported perceived readiness on test days. Resistance exercise session versus no exercise did not differ for TTE (approximately 3min above) (mean ± 95% confidence interval = 3.6% ± 6.0%; P = .29; effect size [ES], Cohen d = 0.27), 30-m DP pre (-0.56% ± 0.80%; P = .21; ES = 0.20), 30-m DP post (-0.18% ± 1.13%; P = .76; ES = 0.03), countermovement jump (-2.0% ± 2.8%; P = .21; ES = 0.12), DP oxygen cost (-0.13% ± 2.04%; P = .91; ES = 0.02), or perceived readiness (P ≥ .11). Electrical stimulation force was not different in contraction or relaxation time but revealed low-frequency fatigue in the afternoon for the resistance exercise session only (-12% [7%]; P = .01; ES = 1.3). A single session of heavy-load, low-volume resistance exercise in the morning did not increase afternoon DP performance of short duration in high-level skiers. However, leg low-frequency fatigue after resistance priming, together with the presence of small positive effects in 2 out of 3 DP tests, may indicate that the preconditioning was too strenuous.

No correlation between symmetry-based performance measures and patient-related outcome prior to and after total knee arthroplasty.

Standardized outcome measures are crucial for the evaluation of different treatment and rehabilitation regimes in patients after total knee arthroplasty (TKA). Performance-based measures are necessary to capture different aspects of physical function. High reliability and agreement of five performance-based measures were hypothesized to differentiate between measurement error and change in test performance. Secondary outcomes are the correlation of performance-based measurements to KSS and WOMAC prior to surgery (baseline) and 10weeks thereafter (t3). The test-retest reliabilities and agreements of the 1-m walk test, the stair-climbing test, the timed-up-and-go test, the weight-balanced-chair-rising test and the isometric maximum knee extension force in patients undergoing total knee replacements were studied. The intraclass correlation coefficient was calculated and a Bland-Altman analysis performed. The weight-balanced-chair-rising test showed a symmetry at baseline = 0.77, 5 ± 1days after surgery (t1) = 0.50, 9 ± 1days (t2) = 0.59 and (t3) = 0.80. All performance tests showed high intraclass correlation coefficients (ICC = 0.81-0.99). The 10-m walk test, stair climbing test, and the timed-up-and-go test showed high agreement in the Bland-Altman analysis. The Bland-Altman analysis for the weight-balanced-chair-rising test and isometric knee extension force indicated high agreement at 5 and 9days postoperatively, but the relative measurement error increased pre- and 10weeks postoperatively. In conclusion, symmetry, as an important outcome after TKA, is a reliable and rather unique item that should unquestionably be added to established measurements like walking tests or survey-based function assessment. The implementation of standardized performance-based measures to assess physical function in rehabilitation procedures will help to improve the more objectively based assessment of different rehabilitation protocols. II.

Fish Protein Ingestion Induces Neural, but Not Muscular Adaptations, Following Resistance Training in Young Adults.

Purpose: Nutritional supplementation in conjunction with exercise is of interest for the prevention or improvement of declines in motor performances in older adults. An understanding of the effects on both young and older adults contributes to its effective application. We investigated the effect of fish protein ingestion with resistance training on neural and muscular adaptations in young adults using interventions and assessments that have already been tested in older adults.Methods: Eighteen young adults underwent 8 weeks of isometric knee extension training. During the intervention, nine participants ingested 5 g of fish protein (n = 9, Alaska pollack protein, APP), and the other nine participants ingested casein as a control (n = 9, CAS) in addition to daily meals. Before, during, and after the intervention, the isometric knee extension force, lower extremity muscle mass, and motor unit firing pattern of knee extensor muscles were measured.Results: Maximum voluntary contraction (MVC) was significantly increased in both APP and CAS groups from 0 weeks to 4, 6, and 8 weeks of intervention (p < 0.001), but there were no significant differences between the groups (p = 0.546–0.931). Muscle mass was not significantly changed during the intervention in either group (p = 0.250–0.698). Significant changes in motor unit firing rates (p = 0.02 and 0.029 for motor units recruited at 20–40% of MVC and at 40–60%) were observed following the intervention in the APP but not CAS (p = 0.120–0.751) group.Conclusions: These results suggest that dietary fish protein ingestion changes motor unit adaptations following resistance training in young adults.

History-Dependence of Muscle Excitation and Oxygenation During Isometric Knee Extension Force Production

PURPOSE:This study examined the issue of history-dependence on muscle excitation and oxygenation by using surface electromyography (EMG) and near-infrared spectroscopy (NIRS).METHODS: Eight male participants performed isometric knee extension force production tasks that started at four levels of initial force production (30, 40, 60, 70% of maximal voluntary contraction, MVC) and commonly converged to the production of 50% of MVC by increasing or decreasing knee extension forces. We quantified the integrated electromyogram (iEMG), total hemoglobin (tHb), and the desaturation rate of muscle tissue (TSI&lt;sub&gt;SLOPE&lt;/sub&gt;) of the vastus lateralis and compared the differences in the quantified variables between the experimental conditions.RESULTS: For the four levels of initial forces production, all the variables showed significant linear relationships with outcome forces. However, the magnitudes of the variables were varied depending on the contraction history at the terminal phase where the identical level of force production (50% of MVC) was required. At the terminal phase, the iEMG was affected by the time history of both mode (e.g., increment or decrement) and magnitude (e.g., 10% or 20% change of MVC), while the tHb and TSI&lt;sub&gt;SLOPE&lt;/sub&gt; showed significant differences between the time history of mode only.CONCLUSIONS:The main result of the current study demonstrates the history-dependence of the changes in physiological demands in muscle activation. In particular, the indices of muscle excitation and oxygenation at the same level of force were varied depending on the time history of contraction, which implies the indices of muscle excitation and oxygenation may not be invariant component to specify the levels of outcome forces.

Effectiveness of impedance parameters for muscle quality evaluation in healthy men

We investigated the relationship between impedance parameters and skeletal muscle function in the lower extremities, as well as the effectiveness of impedance parameters in evaluating muscle quality. Lower extremity impedance of 19 healthy men (aged 23–31 years) measured using the direct segmental multi-frequency bioelectrical impedance analysis were arc-optimized using the Cole–Cole model, following which phase angle (PA), {R}_{i}/{R}_{e}, and β were estimated. Skeletal muscle function was assessed by muscle thickness, muscle intensity, and isometric knee extension force (IKEF). IKEF was positively correlated with PA (r = 0.58, p < 0.01) and β (r = 0.34, p < 0.05) was negatively correlated with {R}_{i}/{R}_{e} (r = − 0.43, p < 0.01). Stepwise multiple regression analysis results revealed that PA, β, and {R}_{i}/{R}_{e} were correlated with IKEF independently of muscle thickness. This study suggests that arc-optimized impedance parameters are effective for evaluating muscle quality and prediction of muscle strength.

Telomere shortening is associated with poor physical performance in knee osteoarthritis.

Telomere length is a hallmark characteristic of ageing and age-related diseases. Osteoarthritis (OA) is the most common cause of joint pain and physical disability in the elderly. Previous studies have revealed the role of telomere shortening in OA; however, the relationship between telomere length, muscle strength and physical performance in knee OA patients remains unknown. The aim of the present study was to investigate the association of telomere length and physical performance in patients with knee OA. A total of 202 patients with knee OA and 60 healthy controls were enrolled in the study. The quality of life was assessed using Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index and Short Form Health Survey. The skeletal muscle mass was examined using bioelectrical impedance analysis, while the muscle strength was analyzed using hand grip force and isometric knee extension force. The physical performance of patients with knee OA was also investigated using gait speed, Timed up and go test (TUGT), Sit to stand test and 6-min walk test (6MWT). Blood leukocyte relative telomere length (RTL) was assessed using real time quantitative PCR. The mean blood leukocyte RTL in knee OA subjects was significantly lower compared with healthy controls (P<0.001). Knee OA patients with RTL values in the lowest quartile had a slow gait speed (P=0.006) and prolonged TUGT time (P=0.03). Multivariate regression analyses and multiple logistic regression analyses adjusted for age, sex, waist circumference, body mass index, fat mass, skeletal muscle index and the total WOMAC demonstrated that gait speed, TUGT and 6MWT were associated with longer RTL (P-trend<0.05). These findings suggested that poorer physical performance was associated with shorter RTL. Therefore, leukocyte telomere length and physical performance tests, especially gait speed, TUGT and 6MWT, could predict the health status and quality of life in patients with knee OA.

Decreased ankle and hip isometric peak torque in young and middle-aged adults with chronic ankle instability

ObjectivesTo compare ankle, knee and hip isometric peak torque between young and middle-aged adults with CAI, copers and un-injured controls. DesignCross-sectional. SettingResearch Laboratory. ParticipantsOne hundred fifty-six young and middle-aged adults with or without CAI volunteered. Main outcome measuresA handheld dynamometer measured isometric dorsiflexion, plantarflexion, knee extension, hip extension and hip abduction peak force during a 5 s trial. Average peak torque was calculated and normalized to body mass. ResultsA significant Age by Injury interaction for dorsiflexion suggest middle-aged un-injured controls (p < 0.001) and copers (p < 0.001) had lower isometric peak torque compared to their young adult counterparts, but there were no differences between young and middle-aged adults with CAI (p > 0.05). Significant Injury main effects suggest the CAI group had decreased plantarflexion (p = 0.004) and hip extension (p = 0.010) strength compared to un-injured controls, but not copers (p > 0.05). Significant Age main effects for all primary outcome measures were observed, indicating peak torque decreased with age (p < 0.05). ConclusionsRegardless of age, isometric ankle and hip peak torque was lower in participants with CAI compared to un-injured controls, but not copers. These findings provide further evidence towards the impact of CAI in both young and middle-aged adults.

Does age of patients with gastrointestinal cancer impact postoperative physical function and quality of life? A prospective study using the new Japanese elderly standard.

[Purpose] The purpose of this study was to investigate the relationship among aging factors using the new Japanese elderly standard, early postoperative physical function, and health-related quality of life (HRQOL) in patients with gastrointestinal cancer. [Participants and Methods] We studied 94 patients scheduled for elective surgery of gastrointestinal cancer: 53 males and 41 females aged 62.0 ± 12.1 years (mean ± SD). Patients were divided into three groups based on age at baseline: young (<65 years), pre-old (65–74 years), and old (≥75 years) groups. We measured body mass index, isometric knee extension force (IKEF), 6-minute walk test (6MWT), and Short-Form 36-Item Health Survey version 2 (SF-36) at baseline and 4 weeks after surgery. [Results] Patients 75 years or older had significantly lower IKEF and 6MWT compared to the other groups. Patients younger than 65 years had significantly greater scores on the mental health SF36 subscale 4 weeks after surgery compared to baseline. Comparatively, patients older than 75 years had significantly decreased mental health scores 4 weeks after surgery. [Conclusion] Based on the new Japanese elderly standard, advanced age appears to worsen the postoperative change of HRQOL in patients with gastrointestinal cancer.

Physical fitness profile in female horseback riders.

The purpose of the present study was to examine the levels of endurance and neuromuscular performance variables in female horseback riders. 52 female Finnish riders were involved (age 29.4±8.9 yrs, height 1.68±0.06 m, weight 67.5±10.0 kg), 19 show-jumping riders (SJ) and 33 eventing riders (E), riding-time minimum of 4 times/week, jumping level of minimum 1.06±0.11m. The measurements were maximal bilateral isometric leg press force (MVCLP), maximal unilateral isometric knee extension (MVCKE) and flexion forces (MVCKF), countermovement jump (CMJ), maximal isometric force of the trunk extensor and flexor muscles (MVCE, MVCF), weight distribution of the body (WD), handgrip strength (HGS), maximal oxygen uptake (VO2max), lactate threshold (L) and heart rate (HR). Mean force in MVCLP was 1887(±455) N, MVCKE right/left 633(±134)/628(±138) N and MVCKF right/left 420(±79)/411(±74) N, respectively. CMJ height was 19.8(±3.9) cm and trunk forces in MVCE 51.2(±13.7) kg and MVCF 61.3(±11.4) kg. Mean WD in the right/left side was 50.5(±2.2)/49.5(±2.2) % and mean HGS of the right/left hand 39.9(±5.1)/39.2(±4.9) kg, respectively. Mean VO2max in the cycle ergometer test was 32.1(±4.5) mL/kg/min, HRmax 184.5(±9.6) beat/min, timemax to exhaustion 18.50(±2.50) min and Lmax 10.2(±2.1) mmol/L. SJ and E groups did not differ significantly from each other in any of the variables. MVCLP, MVCE and MVCF were at about the same level but VO2max somewhat below compared to non-athletic Finnish women of the same age. It would seem that the present female riders would obtain benefits from additional strength training for both maximal and explosive strength gains.

Concurrent validity of a fixated hand-held dynamometer for measuring isometric knee extension strength in adults with congenital heart disease

Purpose: The purpose of this study was to examine the concurrent validity of a fixated hand-held dynamometer (HHD) in comparison to a load cell in measurement of maximal isometric knee extension force in adults with congenital heart disease (CHD) and healthy adults.Methods: Fourteen adults with CHD and fourteen healthy adults were included. Each participant was tested three times with each method and the mean of the top two results for each participant and method was used in analysis.Results: The agreement between the two methods was excellent in both groups (intraclass correlation coefficient [ICC], 95% confidence interval [CI]) 0.98 (0.92–1.00) in the CHD group and ICC 0.99 (0.96–1.00) in the healthy group). There was a small difference of 19.5 Newton or 4.8% (p<.05) between the two methods in the CHD group. No significant difference was seen between the two methods in the healthy group (p>.05).Conclusions: The fixated HHD demonstrated excellent concurrent validity when compared to a load cell among adults with CHD as well as in healthy adults. Thus, in a healthy population the methods can be used interchangeably, however, a small difference between the methods is seen in the CHD group.