THE EFFECT OF ,FATIGUE ON SINGLE-LEG HOP BIOMECHANICS

The single-leg hop is a commonly-used clinical test for patients with knee pathology (e.g. ACL injury). There is currently little information in the literature regarding the biomechanics of this test. However, studies of drop-landings have shown that substantial extensor moments are needed at the hip, knee and ankle to balance and support the body upon ground contact. (Decker et ai., 2003) Total support moment represents the total extensor pattern of the lower extremity to support the body and has been used previously to measure support and balance strategies during the single-limb stance phase of gait. (Winter et al., 1990) When applied to the single-leg hop, this concept may prove useful in analyzing changes in support strategies due to fatigue or injury. The purpose of this study was to compare landing support strategies of the lower extremity before and after fatigue

Countermovement Jump Recovery in Professional Soccer Players Using an Inertial Sensor

Purpose The purpose of this study was to assess the utility of an inertial sensor for assessing recovery in professional soccer players. Methods In a randomized, crossover design, 11 professional soccer players wore shorts fitted with phase change material (PCM) cooling packs or uncooled packs (control) for 3 h after a 90 minute match. Countermovement jump (CMJ) performance was assessed simultaneously with an inertial sensor and an optoelectric system, pre match, and 12, 36 and 60 h post match. Inertial sensor metrics were flight height, jump height, low force, countermovement distance, force at low point, rate of eccentric force development, peak propulsive force, maximum power, and peak landing force. The only optoelectric metric was flight height. CMJ decrements, and effect of PCM cooling were assessed with repeated measures ANOVA. Jump heights were also compared between devices. Results For the inertial sensor data there were decrements in CMJ height on the days after matches (88±10% of baseline at 36 h P=0.012, effect size 1.2, for control condition) and accelerated recovery with PCM cooling (105±15% of baseline at 36 h, P=0.018 vs. control, effect size 1.1). Flight heights were strongly correlated between devices (r=0.905, P<0.001) but inertial sensor values were 1.8±1.8 cm lower (P=0.008). Low force during countermovement was increased (P=0.031) and landing force was decreased (P=0.043) after matches, but neither were affected by the PCM cooling intervention. Other CMJ metrics were unchanged after matches. Conclusions This small portable inertial sensor provides a practical means of assessing recovery in soccer players

Acceptability and feasibility of magnetic femoral nerve stimulation in older, functionally impaired patients

Abstract Objective Magnetic femoral nerve stimulation to test muscle function has been largely unexplored in older people. We assessed acceptability, feasibility, along with reproducibility and correlation with other physical function measures. Results Study 1 recruited older people with sarcopenia. Stimulation was performed at baseline and 2 weeks along with six minute walk (6MW), maximum voluntary quadriceps contraction, short physical performance battery and grip strength. Acceptability was measured using visual analog scales. Study 2 used baseline data from a trial of older people. We correlated stimulation results with 6MW, maximal voluntary contraction and muscle mass. Maximum quadriceps twitch tension was measured in both studies, evoked using biphasic magnetic stimulation of the femoral nerve. In study 1 (n = 12), magnetic stimulation was well tolerated with mean discomfort rating of 9% (range 0–40%) on a visual analog scale. Reproducibility was poor (intraclass correlation coefficient 0.06; p = 0.44). Study 2 (n = 64) showed only weak to moderate correlations for maximum quadriceps twitch tension with other measures of physical function (6 minute walk test r = 0.24, p = 0.06; maximal voluntary contraction r = 0.26; p = 0.04). We conclude that magnetic femoral nerve stimulation is acceptable and feasible but poorly reproducible in older, functionally impaired people

Valorisation of the dry stone wall heritage of the Cres-Lošinj archipelago

The aim of this thesis was to capture the extensiveness and values of an important component of the Croatian Adriatic landscapes – namely, the heritage of the dry stone structures. Current scientific considerations still fail to capture their prevalence and significance despite their increasing relevance in the discourse of scientific research, spatial planning and cultural protection. In this thesis, valorisation comprised a multi-aspect approach, with the Cres-Lošinj archipelago used as a case study area. By combining a GIS-based cartographic production and processing, along with the in-situ recording of the dry stone artefacts accompanied by ethnographic notations, the objective was to lay a foundation and understanding of their distribution and characteristics. This task was followed by a correlation of the dry stone wall landscape-scale patterns to local historical socioeconomic circumstances to address the queries of time-depth data of their structures. Finally, the benefits arising from the dry stone walls were reviewed, especially those appurtenant to the ecosystem services framework, to assist future monetary valuation approaches. The research results include the full quantification and establishment of a GIS database of the dry stone walls of the Cres-Lošinj archipelago, a review and assessment of the heritage diversity and use and its distinctiveness in the context of the Croatian Adriatic and within. Dry stone wall patterns demonstrated their scientific value as indicators of historical events. With the example of the Cres olive grove, another lens of valorisation was discussed – namely, recognition under the cultural landscape category. Finally, initial steps for the conceptualisation of a valuation model were provided.The aim of this thesis was to capture the extensiveness and values of an important component of the Croatian Adriatic landscapes – namely, the heritage of the dry stone structures. Current scientific considerations still fail to capture their prevalence and significance despite their increasing relevance in the discourse of scientific research, spatial planning and cultural protection. In this thesis, valorisation comprised a multi-aspect approach, with the Cres-Lošinj archipelago used as a case study area. By combining a GIS-based cartographic production and processing, along with the in-situ recording of the dry stone artefacts accompanied by ethnographic notations, the objective was to lay a foundation and understanding of their distribution and characteristics. This task was followed by a correlation of the dry stone wall landscape-scale patterns to local historical socioeconomic circumstances to address the queries of time-depth data of their structures. Finally, the benefits arising from the dry stone walls were reviewed, especially those appurtenant to the ecosystem services framework, to assist future monetary valuation approaches. The research results include the full quantification and establishment of a GIS database of the dry stone walls of the Cres-Lošinj archipelago, a review and assessment of the heritage diversity and use and its distinctiveness in the context of the Croatian Adriatic and within. Dry stone wall patterns demonstrated their scientific value as indicators of historical events. With the example of the Cres olive grove, another lens of valorisation was discussed – namely, recognition under the cultural landscape category. Finally, initial steps for the conceptualisation of a valuation model were provided

The Effect of Carbohydrate Beverage Ingestion on Central versus Peripheral Fatigue: A Placebo-Controlled, Randomized Trial in Cyclists

Purpose: We investigated whether carbohydrate ingestion delays fatigue in endurance-trained cyclists via peripheral or central mechanisms. Methods: Ten men [35±9 yrs] and ten women [42±7 yrs] were assigned, in a double-blind, cross-over design to a sports drink [CHO] and placebo [PL]. Strength measures were made 3 times [pre-exercise, post-time trial and post-ride to exhaustion]: 1) Maximal voluntary contraction [MVC]; 2) MVC with superimposed femoral nerve magnetic stimulation to measure central activation ratio [CAR]; 3) femoral nerve stimulation in a 3-second pulse train on relaxed muscle. Subjects cycled 2 hours at ~65% of peak oxygen consumption [VO2peak], with 5 1-minute sprints interspersed, followed by a 3-km time trial. After strength testing, cyclists remounted their bikes, performed a brief warmup, and pedaled at ~85% VO2peak until unable to maintain workload. Changes in metabolic and strength measurements were analyzed with repeated measures ANOVA. Results: From pre-exercise to post-time trial: MVC declined in men (17%) and women (18%) [p=0.004] with no effect of beverage [p>0.193]; CAR decreased in both sexes with PL [P=0.009], the decline was attenuated by CHO in men only [time×treatment, p=0.022]; there was no evidence of peripheral fatigue in either sex with either beverage [p>0.122]. Men rode faster in the time trial with CHO [p=0.005] but did not improve performance in the ride to exhaustion [p=0.080]. In women, CHO did not improve performance in the time trial [p=0.173], or in the ride to exhaustion [p=0.930]. Conclusion: Carbohydrate ingestion preserved central activation and performance in men, but not women, during long-duration cycling.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The 2- and 8-week effects of decompressive brace use in people with medial compartment knee osteoarthritis

BACKGROUND: Knee osteoarthritis is a prevalent disease. Unloading the affected compartment using a brace is a treatment option. OBJECTIVES: To determine whether a decompressive knee brace alters loading in medial knee osteoarthritis following 2 and 8 weeks of use. STUDY DESIGN: Within subjects; pre- and post-testing. METHODS: A total of 15 individuals with medial knee osteoarthritis attended four sessions: baseline, fitting, 2 weeks after fitting (post), and 8 weeks after fitting (final). A gait analysis was performed at baseline (without knee brace), post and final. Knee adduction impulse, first and second peak knee adduction moment, knee motion, and walking velocity were calculated. Participants also recorded hours and steps taken while wearing the brace. RESULTS: On average, the brace was worn for more than 6 h/day. Through use of repeated-measures analysis of variance, it was determined that the knee adduction impulse and second peak knee adduction moment were reduced (p \u3c 0.05) at post and final compared to baseline (36% and 34% reduction in knee adduction impulse, 26% reduction in second peak knee adduction moment for post and final, respectively). Furthermore, participants walked faster with increased knee motion during stance. CONCLUSION: The studied decompressive brace was effective in reducing potentially detrimental forces at the knee-knee adduction impulse and second peak knee adduction moment during the stance phase of gait. CLINICAL RELEVANCE: The data from this study suggest that use of a medial unloading brace can reduce potentially detrimental adduction moments at the knee. Clinicians should use this evidence to advocate for use of this noninvasive treatment for people presenting with medial knee osteoarthritis