Saturday, December 17, 2011
Friday, December 16, 2011
Effect of Functional Knee Brace Use on Acceleration, Agility, Leg Power and Speed Performance in Healthy Athletes
Posted: 12/08/2011; Br J Sports Med. 2011;45(15):1230-1237. © 2011 BMJ Publishing Group Ltd & British Association of Sport and Exercise Medicine
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- Abstract and Introduction
- Methods
- Results
- Discussion
- Conclusions
Abstract and Introduction
Abstract
Objectives To investigate performance levels and accommodation period to functional knee brace (FKB) use in non-injured braced subjects while completing acceleration, agility, lower extremity power and speed tasks.
Design A 2 (non-braced and braced conditions) × 5 (testing sessions) repeated-measures design.
Methods 27 healthy male athletes were provided a custom fitted FKB. Each subject performed acceleration, agility, leg power and speed tests over 6 days; five non-braced testing sessions over 3 days followed by five braced testing sessions also over 3 days. Each subject performed two testing sessions (3.5 h per session) each day. Performance levels for each test were recorded during each non-braced and braced trial. Repeated measures analysis of variance, with a post hoc Tukey's test for any test found to be significant, were used to determine if accommodation to FKB was possible in healthy braced subjects.
Results Initial performance levels were lower for braced than non-braced for all tests (acceleration p=0.106; agility p=0.520; leg power p=0.001 and speed p=0.001). However, after using the FKB for approximately 14.0 h, no significant performance differences were noted between the two testing conditions (acceleration non-braced, 0.53±0.04 s; braced, 0.53±0.04 s, p=0.163, agility non-braced, 9.80±0.74 s; braced, 9.80±0.85 s, p=0.151, lower extremity power non-braced, 58±7.4 cm; braced, 57±8.1 cm, p=0.163 and speed non-braced, 1.86±0.11 s; braced, 1.89±0.11 s, p=0.460).
Conclusions An initial decrement in performance levels was recorded when a FKB is used during an alactic performance task. After 12.0–14.0 h of FKB use, performance measures were similar between the two testing conditions.
Thursday, December 15, 2011
Tuesday, November 15, 2011
Monday, November 14, 2011
Friday, November 11, 2011
Thursday, November 10, 2011
Tuesday, November 8, 2011
Saturday, November 5, 2011
Thursday, November 3, 2011
Saturday, October 29, 2011
Wednesday, October 26, 2011
Friday, October 21, 2011
Monday, October 17, 2011
Friday, October 14, 2011
Monday, October 10, 2011
Wednesday, October 5, 2011
Tuesday, October 4, 2011
Friday, September 30, 2011
Wednesday, September 28, 2011
Muscle power attenuation by tendon during energy dissipation
Muscle power attenuation by tendon during energy dissipation
+ Author Affiliations
- ↵*Author for correspondence (nkonow@brown.edu).
Abstract
An important function of skeletal muscle is deceleration via active muscle fascicle lengthening, which dissipates movement energy. The mechanical interplay between muscle contraction and tendon elasticity is critical when muscles produce energy. However, the role of tendon elasticity during muscular energy dissipation remains unknown. We tested the hypothesis that tendon elasticity functions as a mechanical buffer, preventing high (and probably damaging) velocities and powers during active muscle fascicle lengthening. We directly measured lateral gastrocnemius muscle force and length in wild turkeys during controlled landings requiring rapid energy dissipation. Muscle-tendon unit (MTU) strain was measured via video kinematics, independent of muscle fascicle strain (measured via sonomicrometry). We found that rapid MTU lengthening immediately following impact involved little or no muscle fascicle lengthening. Therefore, joint flexion had to be accommodated by tendon stretch. After the early contact period, muscle fascicles lengthened and absorbed energy. This late lengthening occurred after most of the joint flexion, and was thus mainly driven by tendon recoil. Temporary tendon energy storage led to a significant reduction in muscle fascicle lengthening velocity and the rate of energy absorption. We conclude that tendons function as power attenuators that probably protect muscles against damage from rapid and forceful lengthening during energy dissipation.
Wednesday, September 21, 2011
Wednesday, September 14, 2011
Tuesday, September 13, 2011
Monday, September 12, 2011
Friday, September 9, 2011
Thursday, September 8, 2011
From Reuters Health Information
"Eccentric" Exercises May Ward off Hamstring Injuries
By Genevra Pittman
NEW YORK (Reuters Health) Aug 26 - Pro and amateur soccer players who regularly did a particular strengthening exercise were less likely to get sidelined with a hamstring injury, according to a new study from Denmark.
The exercises only take about 10 minutes, and can be done without any extra equipment, researchers said.
Hamstring strains are the most common injury among soccer players, and "it's also the injury that takes out the most days from training and matches," said study author Dr. Per Holmich, from the University of Copenhagen.
The injuries typically happen when players are sprinting and the hamstrings extend to prevent the knee from overstretching. That tension while the muscle is extending is known as eccentric contraction.
It means very high pressure on the muscles, sometimes for long periods of time, Holmich said.
He and his colleagues figured that mimicking that type of pressure in a strengthening exercise might mean the hamstrings were more prepared to deal with high force in practices or matches.
The researchers studied 50 professional and amateur men's soccer teams in Denmark during a full year of practice and play. They trained coaches on half of the teams to lead "eccentric training" exercises during a midseason break and then regularly during the season.
To do the exercises, players pair up, with one athlete on his knees and the other holding the back of the first player's legs and ankles to the ground. The kneeling player slowly leans forward while holding his weight back with his hamstrings, until reaching a push-up position, then pushes himself back up once he hits the ground.
Teams did those exercises up to three times a week during the 10-week break between seasons, then once a week once matches were underway.
Other teams followed their normal training plan with no extra hamstring exercises.
The study involved a total of 942 players. By the end of the year, 67 of them had suffered a hamstring injury -- 15 that did strengthening exercises, and 52 in the training-as-usual group. Athletes that had the strength training were less likely both to get new hamstring injuries and to aggravate a past hamstring injury.
When athletes did get injured, however, there was no difference in how long they were out as a result -- about four weeks in both groups, on average.
Researchers reported online August 8th in the American Journal of Sports Medicine that, based on usual hamstring injury rates, 13 players would have to regularly undergo the strengthening exercises to prevent one injury.
None of the players got injured during the exercises themselves, although they did report muscle soreness after the early sessions.
Previous studies have suggested that this type of training helps players get stronger, but researchers hadn't randomly assigned teams to do or not do the exercises -- so it was less clear that other factors unique to certain teams weren't behind its apparent benefits.
"This is more or less the final evidence that is needed to be sure that this exercise works," said Roald Bahr, one of the researchers who first proposed this type of training, from the Norwegian School of Sport Sciences in Oslo.
Although Holmich and his colleagues only looked at adult male soccer players, the author said there's no reason to think the strengthening exercises wouldn't also help prevent injuries in younger players and in women.
And, he told Reuters Health, "track and field sprinters as well would probably have a good benefit from doing this exercise."
Bryan Heiderscheit, a physical therapist from the University of Wisconsin--Madison, said the exercises showed promise for many different kinds of athletes, including football running backs and wide receivers.
One of the best things about the exercise, Bahr told Reuters Health, is that "you can do this efficiently, with the whole team, on the pitch, without any additional equipment except maybe a towel or some additional knee padding."
"Every soccer team in the world should be doing it."
For further information: http://www.medscape.com/viewarticle/748641?src=mp&spon=8
Tuesday, August 23, 2011
Double-Bundle Versus Single-Bundle Anterior Cruciate Ligament Reconstruction
Randomized Clinical and Magnetic Resonance Imaging Study With 2-Year Follow-up
- Piia Suomalainen, MD*†,
- Anna-Stina Moisala, MD, PhD‡,
- Antti Paakkala, MD, PhD†,
- Pekka Kannus, MD, PhD§ and
- Timo Järvelä, MD, PhD‡
+Author Affiliations
- ↵* Piia Suomalainen, MD, Teiskontie 35, 33520 Tampere, Finland (e-mail:piia.suomalainen@uta.fi).
Presented at the 36th annual meeting of the AOSSM, Providence, Rhode Island, July 2010.
Abstract
Background: One aspect of the debate over the reconstruction of the anterior cruciate ligament is whether it should be carried out with the single-bundle or double-bundle technique.
Hypothesis: The double-bundle technique results in fewer graft failures than the single-bundle technique in anterior cruciate ligament reconstruction.
Study Design: Randomized controlled trial; Level of evidence, 1.
Methods: A total of 153 patients were prospectively randomized into 2 groups of anterior cruciate ligament reconstruction with hamstring autografts using aperture interference screw fixation: single-bundle technique (SB group, n = 78) and double-bundle technique (DB group, n = 75). The evaluation methods were clinical examination, KT-1000 arthrometric measurement, the International Knee Documentation Committee (IKDC) and the Lysholm knee scores, and magnetic resonance imaging (MRI) evaluation. All of the operations were performed by 1 experienced orthopaedic surgeon, and all clinical assessments were made by 2 blinded and independent examiners. A musculoskeletal radiologist blinded to the clinical data made the MRI interpretation.
Results: There were no differences between the study groups preoperatively. Ninety percent of patients (n = 138) were available at a minimum 2-year follow-up (range, 24-37 months). Eight patients (7 in the SB group and 1 in the DB group) had graft failure during the follow-up and had anterior cruciate ligament revision surgery (P = .04). In addition, 7 patients (5 in the SB group and 2 in the DB group) had an invisible graft on the MRI assessment at the 2-year follow-up. Also, the anteromedial bundle was partially invisible in 2 patients and the posterolateral bundle in 9 patients. Together, the total number of failures and invisible grafts were significantly higher in the SB group (12 patients, 15%) than the DB group (3 patients, 4%) (P = .024). No significant group differences were found in the knee scores or stability evaluations at the follow-up.
Conclusion: This 2-year randomized trial showed that the revision rate of the anterior cruciate ligament reconstruction was significantly lower with the double-bundle technique than that with the single-bundle technique. However, additional years of follow-up are needed to reveal the long-term results.
One-Year Follow-up of Platelet-Rich Plasma Treatment in Chronic Achilles Tendinopathy
A Double-Blind Randomized Placebo-Controlled Trial
- Suzan de Jonge, MD*†‡,
- Robert J. de Vos, MD, PhD‡,
- Adam Weir, MD‡,
- Hans T. M. van Schie, DVM, PhD†§,
- Sita M. A. Bierma-Zeinstra, PhD†‖,
- Jan A. N. Verhaar, MD, PhD†,
- Harrie Weinans, PhD†¶ and
- Johannes L. Tol, MD, PhD‡
+Author Affiliations
- ↵* Suzan de Jonge, MD, Departments of Orthopaedics, Erasmus University Medical Center, PO Box 2040, 3000 CA Rotterdam, the Netherlands (e-mail:s.dejonge@erasmusmc.nl).
Abstract
Background: Achilles tendinopathy is a common disease among both athletes and in the general population in which the use of platelet-rich plasma has recently been increasing. Good evidence for the use of this autologous product in tendinopathy is limited, and data on longer-term results are lacking.
Purpose: To study the effects of a platelet-rich plasma injection in patients with chronic midportion Achilles tendinopathy at 1-year follow-up.
Study Design: Randomized controlled trial; Level of evidence, 1.
Methods: Fifty-four patients, aged 18 to 70 years, with chronic tendinopathy 2 to 7 cm proximal to the Achilles tendon insertion were randomized to receive either a blinded injection containing platelet-rich plasma or saline (placebo group) in addition to an eccentric training program. The main outcome was the validated Victorian Institute of Sports Assessment–Achilles score. Patient satisfaction was recorded and ultrasound examination performed at baseline and follow-up.
Results: The mean Victorian Institute of Sports Assessment–Achilles score improved in both the platelet-rich plasma group and the placebo group after 1 year. There was no significant difference in increase between both groups (adjusted between-group difference, 5.5; 95% confidence interval, −4.9 to 15.8, P= .292). In both groups, 59% of the patients were satisfied with the received treatment. Ultrasonographic tendon structure improved significantly in both groups but was not significantly different between groups (adjusted between-group difference, 1.2%; 95% confidence interval, −4.1 to 6.6, P = .647).
Conclusion: This randomized controlled trial showed no clinical and ultrasonographic superiority of platelet-rich plasma injection over a placebo injection in chronic Achilles tendinopathy at 1 year combined with an eccentric training program.
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