Isokinetics and Exercise Science - Volume 22, issue 4

Authors: Pereira, Maria C. | Bottaro, Martim | Brown, Lee E. | Rocha-Junior, Valdinar A. | Martorelli, Saulo S. | Nóbrega, Otavio T. | Souza, Vinicius C. | Pinto, Ronei S. | Carmo, Jake

Article Type: Research Article

Abstract: BACKGROUND: Athletes often wear compression sleeves, yet studies on their effects are lacking. OBJECTIVE: The aim of this study was to determine the effect of compression sleeves worn during exercise on muscle recovery following exercise. METHODS: Twenty-two resistance trained men were randomly assigned to either a compression sleeve (GCS, n=11) or placebo sleeve (GPS, n=11) group. They performed 4 sets of 10 isokinetic eccentric/concentric elbow flexion repetitions. Isometric peak torque, muscle activation, …echo intensity and perceived muscle soreness were measured at baseline, immediately after and 24, 48, 72 and 96~hours post exercise. Blood CK samples were obtained at baseline, 48 and 96 hours post exercise. RESULTS: There were no significant interactions or main effects for group regarding any of the variables (P > 0.05). There were main effects for time for all variables except muscle activation. Isometric peak torque immediately after and 24, 48, 72 and 96 hours were all significantly less than baseline. Echo intensity immediately after was significantly greater than baseline. Perceived muscle soreness at 48 h was greater than baseline. CK levels at 48 and 96 hours were greater than baseline. CONCLUSIONS: The use of compression sleeves is not recommended for the alleged enhancement of muscle recovery following upper body high-intensity exercise in young resistance-trained men. Show more

Keywords: Elbow flexion, post-exercise, damage marker, resistance, training

DOI: 10.3233/IES-140537

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 265-271, 2014

Authors: Portella, Daniel Leite | Cossio-Bolaños, Marco Antonio | Hespanhol, Jefferson Eduardo | de Arruda, Miguel

Article Type: Research Article

Abstract: BACKGROUND: Few studies thus far have investigated the relationship between body composition (in particular, bone components) and isokinetic strength performance. OBJECTIVE: To determine the relationship between bone mineral content (BMC), bone mineral density (BMD), and fat-free mass (FFM) with isokinetic strength performance variables in professional soccer players. METHODS: We recruited 20 elite male soccer players from the Brazilian league's first division teams. Participants underwent a concentric isokinetic evaluation …of knee flexor and extensor muscles. Dual-energy X-ray absorptiometry (DXA) was used to determine body composition. The relationships between variables were analyzed using Pearson's product-moment correlation coefficient. RESULTS: Body composition variables were correlated with the strength output of knee flexor and extensor muscles in both lower limbs. FFM and BMC explained at least 50% of the variation in peak knee flexion and extension torque while BMD did not have the same effect. CONCLUSIONS: The relationships reported in this study indicate that the use of isokinetics and DXA in soccer players should be further investigated both for measuring athletic performance and for relevant clinical assessment. Show more

Keywords: Isokinetic, strength, fat-free mass, bone components, dual-energy X-ray absorptiometry (DXA)

DOI: 10.3233/IES-140548

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 273-278, 2014

Authors: Lanferdini, Fábio J. | Jacques, Tiago C. | Bini, Rodrigo R. | Vaz, Marco A.

Article Type: Research Article

Abstract: BACKGROUND: Non-specific adaptation from training can elicit similar muscle volume and muscle activation between cyclists and triathletes which differ in comparison to non-athletes. OBJECTIVE: To compare muscle volume, muscle activation and pedal forces of cyclists, triathletes and non-athletes. METHODS: Twelve cyclists, ten triathletes and twelve non-athletes performed an incremental test to determine their maximal power output (PO_{MAX} ). Quadriceps and triceps surae volume were estimated from ultrasound images taken at rest, …while pedal forces and muscle activation were recorded at PO_{MAX} at 90 rpm. RESULTS: Quadriceps volume was larger in cyclists (∼22%, p< 0.04) and triathletes (∼40%, p< 0.01) compared to non-athletes. Higher activation of rectus femoris (∼55%, p=0.01) and tibialis anterior (∼88%, p=0.01) were observed for triathletes compared to non-athletes at the first quarter of the pedaling cycle. Triathletes also showed higher activation for tibialis anterior than cyclists (∼68%, p=0.03) at the first quarter. Non-athletes applied greater force on the pedal compared to triathletes at the first quarter (∼42%, p< 0.01). Pedal force effectiveness was higher for athletes (37–44%, p< 0.02) compared to non-athletes at the fourth quarter. CONCLUSIONS: Similar muscle volume and muscle activation between cyclists and triathletes may be related to a similar training volume supporting differences relative to non-athletes. Show more

Keywords: Electromyography, pedal force, muscle morphology

DOI: 10.3233/IES-140549

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 279-286, 2014

Authors: Kiyama, Ryoji | Kawada, Masayuki | Tokunaga, Ken | Ohwatashi, Akihiko | Fukudome, Kiyohiro | Yone, Kazunori | Yoshimoto, Yoichi | Ohshige, Tadasu | Maeda, Tetsuo

Article Type: Research Article

Abstract: BACKGROUND AND OBJECTIVE: Proprioceptive information from muscle receptors is important in force control and disturbed sensation due to fatigue may reduce the precision of force control. The aim of this study was to clarify the relationship between force sensation and force control ability in knee extensor muscles during fatigue. METHODS: Eighteen healthy young volunteers participated in this study. Force matching tasks with and without feedback were performed immediately before and after the fatigue protocol …consisting of 20 s isometric contractions. The target force was 10% and 30% of the maximal voluntary contraction force in the pre-fatigue protocol. The accuracy of force control ability was estimated by the root mean square error (RMS error) and average difference (average error) between the target and output force. Surface electromyograms were recorded simultaneously from the quadriceps. RESULTS: In the 30% task, there was a significant interaction effect of fatigue and feedback condition in RMS error and average error. RMS error and average error were degenerated significantly by fatigue in the feedback removal condition, but not in the feedback condition. Though the activation of quadriceps was increased by fatigue, increase of muscle activation was lower in the feedback removal condition than that in the feedback conditions. CONCLUSION: Since participants controlled their force output depending on the force sensation in the feedback removal condition, these results indicate that the decline in force sensation may be a significant factor in the decreases of accuracy in force output during fatigue. Show more

Keywords: Force control, force matching, muscle fatigue, knee, isometric contraction

DOI: 10.3233/IES-140550

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 287-293, 2014

Authors: Hatef, Boshra | Bahrpeyma, Farid | Vaziri, Poopak Moatamed

Article Type: Research Article

Abstract: BACKGROUND: Patients with type 2 diabetes mellitus (T2DM) are subject to progressive reduction in muscle strength. However, the effect of T2DM and its duration on muscle endurance is not clear yet. OBJECTIVE: An assessment of force and endurance in short- and long-term diabetes during an isokinetic exercise. METHODS: The peak torqueof knee flexion and extension was recorded for each cycle of 40 isokinetic repetitions of knee flexion/extension at a velocity of 150°/s. Fifty subjects participated …in the study, 18 of whom were diagnosed with diabetes for less than 10 years, 12 subjects with 10 or more years of T2DM and 20 matched healthy control subjects (HC). RESULTS: The endurance index (EI) and the slope of the knee flexor PT curve indicated that patients with long-term T2DM were significantly more resistant to fatigue in comparison to those with short-term T2DM and even to HC subjects. CONCLUSION: Long-term diabetes may cause some muscular adaptation to maintain knee flexor muscle performance during intensive short-term activity. Show more

Keywords: Type 2 diabetes mellitus, isokinetics, muscle endurance, knee muscles

DOI: 10.3233/IES-140551

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 295-301, 2014

Authors: Caruso, John | Barbosa, Amanda | Perry, Rachel | Edwards, Roman | Erickson, Lacey | Potter, William | Keller, Michael

Article Type: Research Article

Abstract: BACKGROUND: ß-Alanine aids exercise performance by increasing intracellular carnosine content. Added carnosine should buffer more H^{ +} produced from exercise and evoke a higher blood lactate concentration ([BLa^{ - } ]) before a person succumbs to fatigue. OBJECTIVE: With a within-subjects design, we compared the effects of placebo (maltodextrin) and ß-alanine administrations on [BLa^{-} ] and average power (AP) values derived from repetitive bouts of lower body supramaximal activity. METHODS: Over separate 30-day …periods, sedentary subjects (n=10) ingested placebo, followed by ß-alanine (3 g ˙ day^{-1} ), capsules. After each period, subjects performed two four-set leg press workouts. [BLa^{-} ] values were measured before, and zero-, five-, ten, 15- and 20-minutes post-exercise. [BLa^{-} ] data underwent a 2 × 6 ANOVA, with repeated measures per independent variable. AP values were compared with a 2 × 4 ANCOVA, with repeated measures per independent variable. RESULTS: AP and [BLa^{-} ] results each included a two-way interaction. ß-alanine elicited higher set two and four AP values versus the corresponding placebo values. [BLa^{-} ] values at zero-minutes post-exercise were significantly higher from ß-alanine, versus the placebo, treatment. CONCLUSIONS: Greater AP and [BLa^{ - } ] values from ß-alanine suggest exercise likely was able to proceed to a greater extent without increasing intracellular acidosis due to a heightened buffer capacity. Show more

Keywords: Blood lactate, average power, acidosis, ergogenic aid

DOI: 10.3233/IES-140552

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 303-309, 2014

Authors: de Oliveira Assumpção, Cláudio | de Lima, Leonardo Coelho Rabello | de Oliveira, Felipe Bruno Dias | Greco, Camila Coelho | Denadai, Benedito Sérgio

Article Type: Research Article

Abstract: BACKGROUND AND OBJECTIVE: Muscle strength imbalance can be an important factor in hamstrings muscle strain. The main purpose of this study was to investigate the effects of downhill running on hamstrings/quadriceps torque (H/Q_{torque} ) and the electromechanical delay (H/Q_{EMD} ) ratios. METHODS: Fifteen active male individuals performed two maximal voluntary isometric contractions of the knee extensors and knee flexors, from which the maximal muscle torque, EMD and H/Q_{torque} …and H/Q_{EMD} ratios were extracted. Thereafter, the participants performed a 30-minute downhill run (−16%) at 70% VO_{2} max. Dependent variables were assessed immediately before, immediately following and 48 hours after the effort. RESULTS: Maximal isometric torque decreased significantly immediately after the downhill run for both the extensors (pre: 271.8 ± 45.9 N˙m; post: 235.5 ± 55.7 N˙m) and flexors (pre: 112.2 ± 26.3 N˙m; post: 97.7 ± 27.2 N˙m). No significant difference was identified over time for the EMD of the vastus lateralis and biceps femoris muscles. The H/Q_{torque} and H/Q_{EMD} ratios were not influenced by the downhill run. CONCLUSION: We have demonstrated that moderate intensity and volume downhill run does not impair knee joint stability at early (H/Q_{EMD} ) and late phases (H/Q_{torque} ) of quadriceps/hamstrings contraction. Show more

Keywords: Strength, fatigue, muscle damage

DOI: 10.3233/IES-140553

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 311-317, 2014

Authors: Pekünlü, Ekim | Özsu, İlbilge

Article Type: Research Article

Abstract: BACKGROUND: The randomization method (RM) is used as a gold standard for creating equal groups in most independent-group design studies. OBJECTIVE: To identify whether the fatigue index (FI)-based matching method could be an alternative for the RM in the context of forming equal independent study groups using relative maximal isometric squat strength (R-MISS) recovery data as the dependent variable. METHODS: Baseline R-MISS values of 30 resistance-trained male participants were assessed. FI was calculated during an exhaustive training …intervention (ETI), including four sets of submaximal isometric squat contractions. Maximal isometric squats were performed 30 seconds, and 2, 4, 6, 8, 10, 12, and 14 minutes after the ETI to assess the recovery levels of R-MISS. For the statistical analyses, low- and high-endurance groups, and two equal-endurance groups (each including 15 participants) were retrospectively formed based on FI scores. RESULTS: The results of the repeated-measures analysis of variance revealed that recovery moments greatly differed (8 minutes) between the high- and low-endurance groups but were similar between the two equal-endurance groups (difference of 2 minutes). Simulations performed using the resampling procedure revealed that the FI-based matching method was more successful than the RM (71.6% vs. 56.2%) in the context of forming equal study groups. CONCLUSIONS: These results indicate that the FI-based matching method is a better alternative to the RM for preventing an unequal distribution of participants among independent groups in R-MISS recovery-related studies. Show more

Keywords: Comparability, fatigue index, isometric contraction, resampling, testing study assumptions

DOI: 10.3233/IES-140554

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 319-331, 2014

Authors: Alt, Tobias | Knicker, Axel J. | Strüder, Heiko K.

Article Type: Research Article

Abstract: BACKGROUND: Although the reliability of isokinetic strength tests of knee flexors (flex) and extensors (ext) has been examined several times, statistical evidence about the influence of internal and external factors is missing. OBJECTIVE: This study aims to examine the impact of familiarisation, muscle group, contraction mode, angular velocity and test parameters on the reproducibility of findings derived from an isokinetic dynamometer (IsoMed 2000). METHODS: Thirty-three male subjects (mean age: 22.3 years) with …no prior experience of isokinetic exercise participated in three identical test sessions (T1, T2, T3), each separated by 48–72 h. Peak moment (PM), angle of peak moment (APM) and contractional work (CW) were determined unilaterally (left and right) during maximum concentric (con) and eccentric (ecc) knee flexion (abdominal position) and extension (supine position) at 30, 90 and 150°/s, respectively. An ANOVA with repeated measures confirmed systematic bias. Reproducibility of consecutive tests (T1–T2, T2–T3) was assessed by calculating the intra-class correlation coefficient (ICC 2,1) (relative reliability) as well as the standard error of measurement (SEM) (absolute reliability). ICC values were averaged according to respective factors (Fisher's z-transformation) and tested for significant differences by Steiger's formulas. RESULTS: PM and CW demonstrated a high absolute reliability (SEM: 4.7–10.5%). Relative reproducibility varied considerably (p⩽ 0.05) between muscles (ecc flex > ecc ext), contraction modes (con ext > ecc ext) and test parameters (PM=CW > APM), but did not depend on angular velocity (30=90=150°/s). Due to familiarisation the reliability of PM obtained from eccentric knee extensions significantly increased (T2–T3 > T1–T2). CONCLUSIONS: These results improve the development and execution of reliable isokinetic strength testing protocols for unilateral knee flexion and extension together with the interpretation of different test parameters. Show more

Keywords: Reproducibility, intra-class correlation coefficient, standard error of measurement, maximum strength testing, familiarisation, IsoMed 2000

DOI: 10.3233/IES-140555

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 333-342, 2014

Authors: Shanbehzadeh, Sanaz | Amiri, Ali | Pirali, Milad | Nassadj, Gholamhossein | Yazdi, Hamid Reza | Jamshidi, Ali Ashraf

Article Type: Research Article

Abstract: BACKGROUND: The single-leg squat (SLS) is a common strengthening exercise after anterior cruciate ligament reconstruction (ACLR) surgery. The multi-joint nature of squatting may allow patients to shift the demand from the target muscle group to its synergies, thus reducing the strengthening effect of the SLS exercise. OBJECTIVE: To compare the muscular contribution in the involved and uninvolved side of the ACLR patients and both sides of the ACLR patients with the matched control group during …SLS exercise. METHOD: Seventeen athletic men with unilateral ACL reconstruction and 16 athletic healthy men participated. Integrated Electromyography was used to calculate the relative contributions of, Vastus Medialis (VM), Vastus Lateralis (VL), rectus femoris (RF), Gluteus maximus (GMax) and Soleus (SOL) muscles to SLS performance and squat peak force was measured with a Biodex System 3 isokinetic dynamometer. RESULTS: The VM muscle contribution was significantly lower and the VL and GMax contribution was higher on the involved side of the ACLR patients compared to their uninvolved side and the control group. The SLS peak force was significantly lower on the involved side compared to the uninvolved side. CONCLUSION: The increased VL and GMax muscle contribution might be a compensatory mechanism for the reduced VM contribution on the involved side. Show more

Keywords: Electromyography, anterior cruciate ligament, single leg squat, isokinetic

DOI: 10.3233/IES-140556

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 343-349, 2014

Article Type: Other

Abstract: Author Index Volume 22 (2014)

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 351-354, 2014

Article Type: Other

Abstract: Keyword Index Volume 22 (2014)

Citation: Isokinetics and Exercise Science, vol. 22, no. 4, pp. 355-356, 2014