Archive for the ‘Uncategorized’ Category

PEAKcontrol is now Sports Medicine Research Laboratory

We’ve recently changed the website address and name of the PEAK Control blog.

The new blog address is:

Please be sure to update your bookmarks.  We will still be posting the same type of content on a regular basis.

We have also changed the name of our Facebook page to UNC Sports Medicine Research Laboratory.  Please be sure to check out and “like” the facebook page as we will routinely post different related content to our facebook page.

Enjoy.  DAP

Categories: Uncategorized

Impact of Diet on Game Performance


Souglis AG, Chryssanthopoulos C, Travlos AK, Zorzou AE, Gissis I, Papadopoulos C, Sotiropoulos A (2012) The effect of high vs. low carbohydrate diets on distances covered in soccer, Journal of Strength and Conditioning Research, doi: 10.1519/JSC.0b013e3182792147

A summary of this recent article can be accessed at the following blog site:

 Brief Summary:

In short, the researchers compared the effects of a high carbohydrate diet to a low carbohydrate diet on measures of work load during a soccer match.  Players consumed either the high (8 g CHO per Kg body mass) or low (3 CHO per Kg body mass) carbohydrate diet for 3.5 days prior to a scheduled game.  An estimated energy and macronutrient content of the prescribed diets during the intervention period for a 70-Kg player is listed below.

High CHO Diet Low CHO Diet
Total Kcal 2869 2873
Carbohydrate (g) 565 212
Fat (g) 44 95
Protein (g) 85 95

Distances traveled during the match were recorded using GPS devices.  Players who consumed high carbohydrate diets traveled significantly greater distances during the soccer match compared to those who consumed a low carbohydrate diet:

  • Total distance covered over entire game: 13% greater in high carbohydrate players
  • Total distance covered in first half: 12% greater in high carbohydrate players
  • Total distance covered in second half: 16% greater in high carbohydrate players

These findings provide insight into the importance of diet / nutrition to actual game related performance.

Is there a link between musculoskeletal injury risk and neurocognitive function?

Over the last few years research has showed an association between neurocognitive test scores and lower extremity musculoskeletal injury risk.  Specifically, decreased neurocognitive scores were observed in those individuals who had suffered lower extremity injury.  These studies have sparked discussion within the research community to better understand the potential relationship between neurocognitive function and lower extremity injury risk.  It is theorized that decreased neurocognitive function may result in poor spatial awareness, slower reaction time, and altered decision making which may facilitate an elevated injury risk.

At this point a cause and effect relationship cannot be established between neurocognitive function and lower extremity injury risk as there is still more research required to better understand this relationship.  However, the current data do suggest that neurocognitive function may be a factor to consider when assessing an individual’s overall injury risk profile.  This information should be along with other data that have also been shown to be related to injury risk, such as movement efficiency, prior injury history, and body mass index.  In addition, neurocognitive function may also be a factor to consider in the rehabilitation and  return to play decision making process, especially in cases of traumatic injury that have resulted in significant time loss.

An overview of the current research examining the relationship between neurocognitive function and musculoskeletal injury can be found at:

Categories: Uncategorized

Lack of Sleep and Increased Injury Risk

Recent research presented at the American Academy of Pediatrics meeting demonstrated that there was a significant relationship between the amount of nightly sleep and the likelihood of injury in a group of middle and high school aged athletes.  Specifically, there was a greater likelihood of injury associated with a lack of nightly sleep.  The press release is copied below.

This research compliments other recent research demonstrating the importance of sleep in those who are engaged in athletics and high levels of physical activity.  Previous research has shown that lack of sleep negatively impacts physical performance in athletes.  This most recent research now shows an association with lack of sleep and increased injury risk.

It is recommended that 8-10 hours of sleep are accumulated throughout the day to achieve peak recovery and avoid negative consequences on physical performance and injury risk.


Press Release:

“For the abstract, “Lack of Sleep is Associated with Increased Risk of Injury in Adolescent Athletes,” researchers asked middle and high school athletes (grades 7 to 12) enrolled at the Harvard-Westlake School in Studio City, Calif., to answer questions about the number of sports they played and the time they committed to athletics (at school and through other programs), whether they used a private coach, whether they participated in strength training, how much sleep they got on average each night, and how much they subjectively enjoyed their athletic participation. Seventy percent of the student athletes (112 out of 160 students; 54 males and 58 females; mean age 15) completed the survey, conducted in conjunction with Children’s Hospital Los Angeles. Researchers then reviewed those students’ school records pertaining to reported athletic injuries.

Hours of sleep per night was significantly associated with a decreased likelihood of injury, according to the study results. In addition, the higher the grade level of the athlete, the greater the likelihood of injury — 2.3 times greater for each additional grade in school. Gender, weeks of participating in sports per year, hours of participation per week, number of sports, strength training, private coaching and subjective assessments of “having fun in sports” were not significantly associated with injury.

“While other studies have shown that lack of sleep can affect cognitive skills and fine motor skills, nobody has really looked at this subject in terms of the adolescent athletic population,” said study author Matthew Milewski, MD.

“When we started this study, we thought the amount of sports played, year-round play, and increased specialization in sports would be much more important for injury risk,” said Dr. Milewski. Instead, “what we found is that the two most important facts were hours of sleep and grade in school.”

The advanced age risk may reflect a cumulative risk for injury after playing three or four years at the high school level, Milewski said, and older athletes are bigger, faster and stronger.”


Categories: Uncategorized

Pre-Season Lockout and Increased Risk of Achilles Tendon Injury

In an editorial written in the Journal of Orthopaedic Sport and Physical Therapy, there was a reported increase in Achilles Tendon injuries in NFL camps this year following the NFL lockout. Typically, the NFL pre-season training periods are spread out over 14 weeks; however, given the NFL lockout the pre-season training periods were reduced to approximately 17 days prior to starting pre-season competitive games.  During the pre-season training and games there were a large number of Achilles Tendon injuries/ruptures reported during this period.  It is suggested that the shortened pre-season training period may have been a major factor leading to the increased number of Achilles Tendon injuries/ruptures.

This information may be particularly relevant considering the shortened pre-season for the NBA athlete this coming year.  While the NBA athlete may has the ability to participate in more game like training compared to an NFL athlete, there is potentially a similar increased risk of injury for the NBA athlete given the shortened training period.  Perhaps more than ever the importance of pre-season screening and corrective exercise training should be emphasized to try and minimize the risk of similar injury trends.

The link below is to an overview posted on this topic.

The abstract below is from the J Orthop and Sports Phys Ther editorial that was published on this topic.


Over the past few months we have been afforded a unique opportunity to evaluate injury rate data prior to, during, and following the historical aberration created by the recent National Football League (NFL) Lockout. During this period (March 11th to July 25th, 2011), professional football players underwent an uncommon offseason, without the normal access to their team’s healthcare providers, strength and conditioning professionals, and high-level coaches. With limited access to these professionals and an absence of the structured preseason preparatory conditioning normally progressed over a 14-week period between May and July, we had a unique window of opportunity to evaluate the effects of an alarmingly rapid transition from the start of training camp, which took place 2 days after the end of the Lockout, to the initiation of preseason competition. A glimpse at early data, limited to Achilles tendon injuries, is cause for concern due to an unprecedented number of Achilles tendon ruptures in training camp and the beginning of preseason.

J Orthop Sports Phys Ther 2011;41(10):702-705. doi:10.2519/jospt.2011.0107


Categories: Uncategorized

Knee Extension Motion Post ACL-Reconstruction Is Associated with Knee Osteoarthritis Within 5-year Post-Surgery

Shelbourne KD, Urch SE, Gray T, Freeman H.  Loss of normal knee motion after anterior cruciate ligament reconstruction is associated with radiographic arthritic changes after surgery.  Am J Sports Med 2011 Oct 11. [Epub ahead of print]

PMID: 21989129

Note: This study examined risk factors for development of radiographic arthritic changes in the knee in those individuals who had ACL reconstruction performed.  The author’s found that knee extension/flexion range of motion measured with a standard goniometer was predictive of future development of knee arthritic changes within 5 years post-surgery.  Most important is that on small differences in knee extension/flexion range of motion compared to the uninjured side were predictive of future knee arthritic changes.  Individuals whose knee extension motion was more than 2-degrees less (this includes hyper-extension) and whose knee flexion motion was more than 5-degrees less than the uninjured side were at greater risk for radiographic arthritic changes in the ACL reconstructed knee.  This indicates how critical it is to achieve SYMMETRIC knee extension/flexion range of motion as part of the early rehabilitation goals following ACL reconstruction.

Clinical Implications: Individuals post ACL reconstruction are at greater risk for radiographic arthritic changes in the knee if their knee extension and flexion is not within 2 and 5-degrees, respectively of the uninjured knee.  Symmetrical knee extension/flexion should be a primary goal of the early rehabilitation process post-ACL reconstruction.  Failure to achieve symmetrical knee extension/flexion will increase the risk of early onset knee osteoarthritis within these individuals.  It is also important to continually monitor knee extension/flexion motion once symmetrical motion has been achieved.  This is especially important as previous research demonstrates that knee extension/flexion motion gains will often be lost several weeks of being achieved if continual focus on maintaining knee motion is not performed.  Thus, we should regularly re-assess knee motion post ACL reconstruction, even after symmetry with the uninjured side is achieved, to ensure that these gains are maintained and that risk of future knee osteoarthritis development is kept at a minimum.

BACKGROUND:  Meniscectomy and articular cartilage damage have been found to increase the prevalence of osteoarthritis after anterior cruciate ligament reconstruction, but the effect of knee range of motion has not been extensively studied.  HYPOTHESIS:  The prevalence of osteoarthritis as observed on radiographs would be higher in patients who had abnormal knee range of motion compared with patients with normal knee motion, even when grouped for like meniscal or articular cartilage lesions.  STUDY DESIGN: Cohort study; Level of evidence, 3.  METHODS: We prospectively followed patients at a minimum of 5 years after surgery. The constant goal of rehabilitation was to obtain full knee range of motion as quickly as possible after surgery and maintain it in the long term. Range of motion and radiographs were evaluated at the time of initial return to full activities (early follow-up) and final follow-up according to International Knee Documentation Committee (IKDC) objective criteria. A patient was considered to have normal range of motion if extension was within 2° of the opposite knee including hyperextension and knee flexion was within 5°. Radiograph findings were rated as abnormal if any signs of joint space narrowing, sclerosis, or osteophytes were present.  RESULTS:  Follow-up was obtained for 780 patients at a mean of 10.5 ± 4.2 years after surgery. Of these, 539 had either normal or abnormal motion at both early and final follow-up. In 479 patients who had normal extension and flexion at both early and final follow-up, 188 (39%) had radiographic evidence of osteoarthritis versus 32 of 60 (53%) patients who had less than normal extension or flexion at early and final follow-up (P = .036). In subgroups of patients with like meniscal status, the prevalence of normal radiograph findings was significantly higher in patients with normal motion at final follow-up versus patients with motion deficits. Multivariate logistic regression analysis of categorical variables showed that abnormal knee flexion at early follow-up, abnormal knee extension at final follow-up, abnormal knee flexion at final follow-up, partial medial meniscectomy, and articular cartilage damage were significant factors related to the presence of osteoarthritis on radiographs. Abnormal knee extension at early follow-up showed a trend toward statistical significance (P = .0544). Logistic regression showed the odds of having osteoarthritis were 2 times more for patients with abnormal range of motion at final follow-up; these odds were similar for those with partial medial meniscectomy and articular cartilage damage.  CONCLUSION: The prevalence of osteoarthritis on radiographs in the long term after anterior cruciate ligament reconstruction is lower in patients who achieve and maintain normal knee motion, regardless of the status of the meniscus.

Categories: Uncategorized

Effects of Isolated Hip Strengthening on Biomechanics During Running and Single-Leg Squat Performance

Will RW, Davis IS.  The effects of a hip-strengthening program on mechanics during running and during a single-leg squat.  J Orthop Sports Phys Ther 41(9):625-632, 2011.

Note: This study demonstrates that a hip strengthening program performed 3-times per week for 6-weeks (exercise examples: side lying hip abduction, standing hip abduction and external rotation against a wall, single leg squat, pelvic hike, side-step with resistance band) does significantly improve hip abduction and external rotation strength.  Furthermore, the hip-strengthening program also significantly changes hip motion during a single leg squat task (e.g. less hip adduction and internal rotation).  Thus, demonstrating improved neuromuscular control of the hip during a single-leg squat task.  However, there were no significant alterations in hip kinematics during a running task.

These findings indicate that changes in running biomechanics are not achieved following a hip-strengthening program.  This may be due to the nature of the exercise program as no exercises were performed over the 6-week intervention period that simulated running.  Thus, the individuals were not able to transfer their improved strength and neuromuscular control to other tasks.  It is possible that more functional/integrated may be required after achieving improved hip strength and single leg squat neuromuscular control to ultimately improve running biomechanics.

Clinical Implications:  While running biomechanics were not improved, this study does demonstrate that hip strengthening is a necessary component to improve neuromuscular contorl during a single leg squat task.  Therefore, including these types of exercises in an injury prevention or rehabilitation program to improve hip strength and neuromuscular control is supported.


STUDY DESIGN: Block randomized controlled trial. OBJECTIVES: To investigate whether a strengthening and movement education program, targeting the hip abductors and hip external rotators, alters hip mechanics during running and during a single-leg squat. BACKGROUND: Abnormal movement patterns during running and single-leg squatting have been associated with a number of running-related injuries in females. Therapeutic interventions for these aberrant movement patterns typically include hip strengthening. While these strengthening programs have been shown to improve symptoms, it is unknown if the underlying mechanics during functional movements is altered. METHODS: Twenty healthy females with excessive hip adduction during running, as determined by instrumented gait analysis, were recruited. The runners were matched by age and running distance, and randomized to either a training group or a control group. The training group completed a hip strengthening and movement education program 3 times per week for 6 weeks in addition to single-leg squat training with neuromuscular reeducation consisting of mirror and verbal feedback on proper mechanics. The control group did not receive an intervention but maintained the current running distance. Using a handheld dynamometer and standard motion capture procedures, hip strength and running and single-leg squat mechanics were compared before and after the strengthening and movement education program. RESULTS: While hip abductor and external rotation strength increased significantly (P<.005) in the training group, there were no significant changes in hip or knee mechanics during running. However, during the single-leg squat, hip adduction, hip internal rotation, and contralateral pelvic drop all decreased significantly (P = .006, P = .006, and P = .02, respectively). The control group exhibited no changes in hip strength, nor in the single-leg squat or running mechanics at the conclusion of the 6-week study. CONCLUSION: A training program that included hip strengthening and movement training specific to single-leg squatting did not alter running mechanics but did improve single-leg squat mechanics. These results suggest that hip strengthening and movement training, when not specific to running, do not alter abnormal running mechanics. LEVEL OF EVIDENCE: Therapy, level 2b.

KEY WORDS: biomechanics, gluteus, knee, lower extremity

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