Geeky Friday is BACK!
Hope you are all ready for another awesome weekend!
Before going on doing stupid stuff (I know you will, and so will I), let’s get a bit smarter first. Here are some of the latest studies carried out in our area of interest. Pick the ones you like, get the full text and knock yourself out!
All best my friends,
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Knee Joint Kinetics in Relation to Commonly Prescribed Squat Loads and Depths.
J Strength Cond Res. 2012 Oct 18;
Authors: Cotter JA, Chaudhari AM, Jamison ST, Devor ST
Abstract: Controversy exists regarding the safety and performance benefits of performing the squat exercise to depths beyond 90° of knee flexion. Our aim was to compare the net peak external knee flexion moments (pEKFM) experienced over typical ranges of squat loads and depths. Sixteen recreationally trained males (n = 16; 22.7 ± 1.1 yrs; 85.4 ± 2.1 kg; 177.6 ± 0.96 cm; mean ±SEM) with no previous lower limb surgeries or other orthopedic issues and at least one year of consistent resistance training experience while utilizing the squat exercise performed single repetition squat trials in a random order at squat depths of above parallel, parallel, and below parallel. Less than one week before testing, one repetition maximum (1RM) values were found for each squat depth. Subsequent testing required subjects to perform squats at the three depths with three different loads: unloaded, 50% 1RM, and 85% 1RM (nine total trials). Force platform and kinematic data were collected to calculate pEKFM. To assess differences among loads and depths, a two-factor (load and depth) repeated-measures ANOVA with significance set at the P < 0.05 level was used. Squat 1RM significantly decreased 13.6% from the above parallel to parallel squat and another 3.6% from the parallel to the below parallel squat (P < 0.05). Net peak external knee flexion moments significantly increased as both squat depth and load were increased (P ≤ 0.02). Slopes of pEKFM were greater from unloaded to 50% 1RM than when progressing from 50% to 85% 1RM (P < 0.001). The results suggest that that typical decreases in squat loads used with increasing depths are not enough to offset increases in pEKFM.
Muscle loading and activation of the shoulder joint during humeral external rotation by pulley and variable resistance.
J Electromyogr Kinesiol. 2012 Jun;22(3):424-30
Authors: Peltonen H, Arokoski J, Kallinen M, Pullinen T
Abstract: BACKGROUND: The aim of the study was to evaluate differences in the loading of glenohumeral joint muscles between a cable pulley machine (CP) and variable resistance machine (VR) during axial humeral external rotation.
METHODS: Eleven healthy male subjects took part in the study. Intramuscular electromyography from five muscles of the shoulder (medial deltoid, supraspinatus, infraspinatus and upper part of the trapezius), torque and power output was measured at different rotation angles and with different loads (10%, 50% and 100% of 1RM). Also the compressive and shear force in the glenohumeral joint was analyzed at the horizontal level at angles of rotation. External rotation was performed with a self-selected velocity on the scapular plane.
FINDINGS: In the CP the range of movement became narrower than in the VR with increasing workload (P<0.05). The activity of the infraspinatus did not grow in the CP after 50% load, while it did in the VR (P<0.01). The upper part of the trapezius was activated less in the CP than in the VR (P<0.01) machine when using 50% and 100% loads. In comparison with the CP, the shear forces that pull the head of the humerus in a posterior direction were more evenly distributed in the VR than in the CP at different angles of rotation (P<0.001).
INTERPRETATION: The VR seems to make a broader range of motion possible, lager activation the primary external rotators and evenly distributed shear forces than the CP. However, performing the exercise with VR and high load also activates the upper part of the trapezius.
RELEVANCE: These findings can be used in the development of exercise designs, methods and equipment for shoulder injury rehabilitation.
Effects of rest interval length on rating of perceived exertion during a multiple-set resistance exercise.
Percept Mot Skills. 2012 Aug;115(1):273-82
Authors: Farah BQ, Lima AH, Lins-Filho OL, Souza DJ, Silva GQ, Robertson RJ, Cyrino ES, Ritti-Dias RM
Abstract: This investigation analyzed the effect of rest interval length on the rating of perceived exertion (RPE) during a resistance exercise session. Nineteen males performed two experimental sessions: resistance exercise with 30-sec. rest intervals (E30) and 90-sec. rest intervals (E90). In both sessions, five exercises (bench press, knee extension, seated row, knee curl, and frontal rise) were performed at 50% 1RM in three sets of 12, 9, and 6 repetitions, respectively. In the E30 session, the RPE increased between sets in all exercises, while in the E90 session, the RPE increased from the first set to the second set in three exercises. RPE in the E30 session was higher than that in the E90 session in the third set. The results suggest that RPE increases for shorter rest intervals than for longer rest intervals. Therefore, the RPE could be considered an indicator of muscle recovery during resistance exercise.
Skeletal Muscle Autophagy and Protein Breakdown Following Resistance Exercise are Similar in Younger and Older Adults.
J Gerontol A Biol Sci Med Sci. 2012 Oct 22;
Authors: Fry CS, Drummond MJ, Glynn EL, Dickinson JM, Gundermann DM, Timmerman KL, Walker DK, Volpi E, Rasmussen BB
Abstract: BACKGROUND: The loss of skeletal muscle mass and strength during aging, sarcopenia, increases the risk for falls and dependency. Resistance exercise (RE) training is effective at improving muscle mass and strength in older adults; however, aging is associated with reduced training-induced hypertrophy. Recent research has illustrated an impaired muscle protein synthetic response following an acute bout of RE in older adults but much less is known regarding the effect of acute RE on muscle protein breakdown (MPB). We hypothesize that the ubiquitin proteasome system and the autophagosomal-lysosomal system may regulate the overall rate of MPB during postexercise recovery. METHODS: Muscle biopsies of the vastus lateralis were sampled from 16 older (age = 70±2 years) and 16 younger (age = 27±2 years) participants at baseline and at 3, 6, and 24 hours following an acute bout of RE. In conjunction with stable isotopic techniques to measure MPB, we utilized immunoblotting and RT-PCR to examine protein and mRNA expression for key signaling molecules in both the ubiquitin proteasome system and the autophagosomal-lysosomal system. RESULTS: MuRF1 mRNA expression increased, whereas GABARAP mRNA decreased after RE in both younger and older adults (p < .05). The LC3B-II/LC3B-I protein ratio decreased in both groups after RE (p < .05), but MPB was not different 24 hour post-RE in either group (p > .05). CONCLUSIONS: Aging does not influence skeletal MPB, autophagy, or the ubiquitin proteasome system following an acute bout of RE. Therefore, targeting the muscle protein synthesis response to exercise may hold more promise in the prevention of sarcopenia.
Effects of two different quadriceps strengthening exercise approaches on cardiovascular fitness in healthy female subjects: a single blind randomized study.
J Back Musculoskelet Rehabil. 2012;25(2):81-7
Authors: Daşkapan A, Tonga E, Durutürk N, Tüzün EH
Abstract: OBJECTIVE: There are limited number of documents showing the relations between cardiovascular fitness and muscle strength. This study aimed to determine the effects of two different quadriceps strengthening exercise approaches on cardiovascular fitness in healthy female subjects.
METHODS: Forty female university students participated in this study on a voluntary basis. The participants were randomly assigned to do either isokinetic exercise (IE) or progressive resistive exercise (PRE) in two different groups. Both training schemes were performed three times a week for a period of two weeks. The subjects were given a maximum symptom limited exercise test on a treadmill before and after (each) training period.
RESULTS: Total exercise duration increased and Borg scale level decreased significantly after training in the two groups (p < 0.05). Maximal systolic blood pressure, recovery heart rate, and recovery diastolic blood pressure decreased significantly in the IE Group (p < 0.05). Resting and recovery systolic blood pressure decreased significantly in the PRE Group (p < 0.05). Compared to PRE group, improvement for Borg Scale level, recovery heart rate and recovery diastolic blood pressure were more obvious in IE Group (p < 0.05).
CONCLUSIONS: This study demonstrated that both quadriceps strengthening methods have displayed improvements in cardiovascular fitness. Further research with larger sample groups may need to be carried out
Trunk muscles strength and endurance in chronic low back pain patients with and without clinical instability.
J Back Musculoskelet Rehabil. 2012;25(2):123-9
Authors: Davarian S, Maroufi N, Ebrahimi I, Farahmand F, Parnianpour M
Abstract: OBJECTIVES: Previous research has shown inconsistent findings regarding muscle endurance in chronic low back pain (CLBP). Questions also remain about muscle endurance in patients with clinical instability. The aim of this study was to investigate trunk muscles strength and endurance in CLBP patients with and without clinical instability.
METHODS: 32 CLBP patients (15 with and 17 without clinical instability) and 39 matched healthy subjects participated in this study. The standing extension test was performed to assess the strength and endurance of the lumbar extensors while recording their electromyographic activity. The patients’ disability was evaluated using the Oswestry and Roland-Morris Disability Questionnaires.
RESULTS: Patients with clinical instability showed lower maximal voluntary exertion (MVE) and higher time to fatigue (TTF) compared to healthy subjects (P=0.000 and P=0.008, respectively) and patients without instability (P=0.002 and P=0.02, respectively). There was no difference in these variables between patients without instability and healthy controls. A negative relationship between MVE and TTF and a positive correlation between disability and pain intensity were seen.
CONCLUSION: Strength training of trunk extensor muscles can be considered as part of the treatment protocol for CLBP patients with clinical instability. Although patients without instability suffered from pain or disability, they showed more similarity to healthy subjects in terms of trunk muscles strength and endurance.
Effects of elastic-band exercise on lower-extremity function among female patients with osteoarthritis of the knee.
Disabil Rehabil. 2012;34(20):1727-35
Authors: Chang TF, Liou TH, Chen CH, Huang YC, Chang KH
Abstract: OBJECTIVE: To investigate a new style of resistance exercise using elastic bands and explore its therapeutic effect on the lower-extremity function of female patients with osteoarthritis (OA) of the knee.
DESIGN: A randomized, controlled clinical trial.
SETTING: University-affiliated medical center.
PARTICIPANTS: Forty-one women with mild-to-moderate knee OA were randomly assigned to one of two groups, an exercise group (n = 24; age: 65.0 ± 8.4 years), and a control group (n = 17; age: 70.8 ± 8.4 years).
INTERVENTIONS: The exercise group performed supervised exercise with elastic bands in addition to conventional modality treatments two to three times a week for 8 weeks. The control group received only the conventional modality treatments over the same period.
MAIN OUTCOME MEASURES: The distance of the functional forward-reach, 30 s chair stand repetitions, walking function (time of a 10 m walk, timed up-and-go, and going up-and-down 13-stair tests), and Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index scores.
RESULTS: Statistically significant improvements in all measures were observed in the exercise group after 8 weeks (p < 0.001). Except for the outcomes on the functional forward-reach (p = 0.108) and going up-and-down 13-stair test (p = 0.278), there were significant differences in the extent of improvement between the two groups. Positive changes in the 30 s chair stand test, 10 m walk test, and timed up-and-go test were 2.5 ± 1.4 repetitions, 1.4 ± 1.2 s, and 1.6 ± 1.1 s in the exercise group, which were significant better than those in the control group (0.6 ± 0.9 repetitions, 0.5 ± 1.1 s, and 0.3 ± 1.1 s, respectively) (p ≤ 0.001). The lower scores of all three subscales of the WOMAC index were significant after 8 weeks (p ≤ 0.05), especially for pain (-2.3 ± 1.3) and physical function (-10.7 ± 5.9) (both p ≤ 0.01), and the improvements were all significant better than those of the control group (p ≤ 0.05).
CONCLUSIONS: A new style of resistance exercise using elastic bands with four color combinations (yellow-red, red-red, red-green, and green-green) over a period of 8 weeks can significantly improve lower-extremity function among females with mild-to-moderate knee OA
Muscular strength and markers of insulin resistance in European adolescents: the HELENA Study.
Eur J Appl Physiol. 2012 Jul;112(7):2455-65
Authors: Jiménez-Pavón D, Ortega FB, Valtueña J, Castro-Piñero J, Gómez-Martínez S, Zaccaria M, Gottrand F, Molnár D, Sjöström M, González-Gross M, Castillo MJ, Moreno LA, Ruiz JR
Abstract: The aim of the study was to examine the association of muscular strength with markers of insulin resistance in European adolescents. The study comprised a total of 1,053 adolescents (499 males; 12.5-17.5 years) from ten European cities participating in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) Cross-Sectional Study. Muscular strength was measured by the handgrip strength and standing long jump tests. Cardiorespiratory fitness was measured by the 20-m shuttle run test. Fasting insulin and glucose were measured and the homeostasis model assessment (HOMA) and quantitative insulin sensitivity check index (QUICKI) indices were calculated. Weight, height, waist circumference and skinfold thickness were measured, and body mass index (BMI) was calculated. In males, the handgrip strength and standing long jump tests were negatively associated with fasting insulin and HOMA (all P < 0.05) after controlling for pubertal status, country and BMI or waist circumference. When skinfold thickness was included in the model, the association became non-significant. In females, the standing long jump test was negatively associated with fasting insulin and HOMA (all P < 0.001) after controlling for pubertal status, country and surrogate markers of total or central body fat (BMI, waist circumference or skinfold thickness). Findings were retained in males, but not in females after controlling for cardiorespiratory fitness. The findings of the present study suggest that preventive strategies should focus not only on decreasing fatness and increasing cardiorespiratory fitness but also on enhancing muscular strength.
Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training.
Eur J Appl Physiol. 2012 Jul;112(7):2767-75
Authors: Metcalfe RS, Babraj JA, Fawkner SG, Vollaard NB
Abstract: High-intensity interval training (HIT) has been proposed as a time-efficient alternative to traditional cardiorespiratory exercise training, but is very fatiguing. In this study, we investigated the effects of a reduced-exertion HIT (REHIT) exercise intervention on insulin sensitivity and aerobic capacity. Twenty-nine healthy but sedentary young men and women were randomly assigned to the REHIT intervention (men, n = 7; women, n = 8) or a control group (men, n = 6; women, n = 8). Subjects assigned to the control groups maintained their normal sedentary lifestyle, whilst subjects in the training groups completed three exercise sessions per week for 6 weeks. The 10-min exercise sessions consisted of low-intensity cycling (60 W) and one (first session) or two (all other sessions) brief ‘all-out’ sprints (10 s in week 1, 15 s in weeks 2-3 and 20 s in the final 3 weeks). Aerobic capacity ([Formula: see text]) and the glucose and insulin response to a 75-g glucose load (OGTT) were determined before and 3 days after the exercise program. Despite relatively low ratings of perceived exertion (RPE 13 ± 1), insulin sensitivity significantly increased by 28% in the male training group following the REHIT intervention (P < 0.05). [Formula: see text] increased in the male training (+15%) and female training (+12%) groups (P < 0.01). In conclusion we show that a novel, feasible exercise intervention can improve metabolic health and aerobic capacity. REHIT may offer a genuinely time-efficient alternative to HIT and conventional cardiorespiratory exercise training for improving risk factors of T2D.
Progressive resistance versus relaxation training for breast cancer patients during adjuvant chemotherapy: Design and rationale of a randomized controlled trial (BEATE study).
Contemp Clin Trials. 2012 Oct 24;
Authors: Schmidt ME, Wiskemann J, Krakowski-Roosen H, Knicker AJ, Habermann N, Schneeweiss A, Ulrich CM, Steindorf K
Abstract: BACKGROUND AND RATIONALE: Cancer-related fatigue is a common severe symptom in breast cancer patients, especially during chemotherapy. Exercise appears to be promising in prevention or treatment of fatigue. Resistance training as an accompanying treatment to chemotherapy has been minimally investigated, yet might counteract muscle degradation and inflammation caused by many chemotherapeutics, and thus forestall or reduce fatigue. Previous exercise trials mostly compared the intervention with ‘usual care’. Therefore, it is unclear to what extent the observed effects on fatigue are based on physical adaptations by exercise itself, or rather on psycho-social factors linked to the group support or attention by the trainer. METHODS AND DESIGN: The BEATE study is a randomized, controlled intervention trial comparing a 12-week supervised progressive resistance training program with a supervised group-based progressive muscle relaxation training in 100 patients with breast cancer under adjuvant chemotherapy. The primary endpoint is cancer-related fatigue; secondary endpoints include quality of life, depression, and cognitive capacity. In addition, isokinetic and isometric muscle strength, cardiorespiratory fitness, and body composition are measured, and biomarkers, such as inflammatory parameters, cortisol, and oxidative stress are analyzed in blood, saliva and urine. Safety of the resistance training during chemotherapy is monitored. DISCUSSION: Strengths of the BEATE study include the investigation of progressive resistance training in parallel to chemotherapy, the choice of a control group that enables an evaluation of the physiological effects of exercise beyond potential psycho-social effects, and the comprehensive and high-quality assessment of physiological factors and biomarkers potentially related to fatigue.