Latest Clinical Research Published by ACSM

Health-related Outcomes Following a Youth Sport-related Knee Injury A ligamentous knee injury in youth greatly increases the risk of developing knee osteoarthritis (OA) as an adult (1). The mechanism for this relationship has been speculated upon, but has not been definitively established. This cohort study from Calgary identified young adults who had sustained a significant knee injury 3 to 10 years previously and compared them on knee pain and function to uninjured matched controls (2). The objective of the study, published in the February 2019 issue of Medicine & Science in Sports & Exercise® (MSSE), was to identify risk factors in these previously injured young adults that made them more susceptible to the developing knee osteoarthritis later in life. Inclusion criteria was a sports-related knee injury as a youth (18 years or younger) 3 to 10 years prior to the chart review. A significant knee injury was defined as the clinical diagnosis of knee ligament or meniscal derangement, or other knee injury, which required both medical consultation and interrupted regular sports participation. Each subject who agreed to participate in the study was matched by sex, age, and sports demands at the time of injury to an uninjured control subject. All subjects were then evaluated for the dependent variables. Current subjective symptoms were assessed by the Knee Injury and Osteoarthritis Outcome Score (KOOS) with subscales for pain, other symptoms, function in daily living, and knee related quality of life. The Intermittent and Constant Osteoarthritis Pain (ICOAP) score also was administered. Physiologic variables included BMI, body composition by dual energy X-ray absorptiometry and aerobic capacity as assessed by the Leger 20-m shuttle run test. Isometric strength in knee extension and flexion and hip abduction and adduction, was measured, and dynamic balance was assessed by three different tests. Knee x-rays and MRI were evaluated for radiographic measures of OA. Data analysis was done by a matched-pair design. To achieve a total of 200 subjects (100 injured, 100 uninjured), 1,591 individuals were contacted. In the final injured study group, 54% had ACL tears (67% of these with concomitant meniscal tears), all of whom had surgery. Fifteen percent had isolated meniscal tears, 47% of whom had surgery. The remainder had other ligamentous injuries (13%), patella-femoral dislocation/subluxation (17%), or fracture (1%). Average age of injury was 16 years (range, 9–18 years), and the average time to follow-up was 6.9 years (range, 3–10 years). Simple analysis by within-pain group differences and subsequent multivariable analysis found that the injured group had poorer KOOS pain scores on all subscales, higher total and intermittent pain scores on the ICOAP, higher BMI and percent body fat, weaker knee flexion and extension, and poorer overall dynamic balance than the uninjured group. Time since injury was associated with more knee symptoms, weaker knee extension strength, and poorer balance on the Triple Single Leg Hop dynamic balance test. In the multivariate analysis, there was no association found between injury history and constant pain on the ICOAP, self-reported weekly physical activity, estimated aerobic capacity, or hip abductor and adductor strength. When comparing ACL tear versus non-ACL-matched groups, an ACL tear was associated with greater intermittent and total pain, reduced aerobic capacity, and lower knee extensor strength. In fact, intermittent and total pain on the ICOAP and knee extensor strength were only significantly different in the ACL-matched groups, not in the other knee injury matched groups. The results of this study are important because they indicate that young adults with a history of a significant knee injury as a child or adolescent have deficits in strength and dynamic balance, higher BMI, as well as persistent pain, 3 to 10 years after their injury. While these deficits were more pronounced in subjects with a history of ACL tears, subjects with other knee injuries also had significant differences when compared to matched controls. Future studies need to be conducted to investigate if correcting these deficits in strength and balance, and preventing weight gain, can decrease their increased risk of developing knee OA as older adults. Bottom Line: Young adults with a history of a significant knee injury have more knee-related pain as well as deficits in knee strength and dynamic balance, and increased BMI, compared with uninjured matched controls when assessed 3 to 10 years after their initial sports-related injury. Effects of Napping on Alertness, Cognitive, and Physical Outcomes of Karate Athletes Everyone likes a nap, but should we encourage it in our athletes? Does a nap prior to competition refresh the athlete and improve performance, or does it make him or her more lethargic? Can a nap make up for poor sleep the night before? The latter question is certainly relevant to athletes who have been shown to often have disrupted sleep the night before a major competition. These are the questions Daaloul and colleagues out of France tried to address in their study of the effects of napping on karate athletes, published in the February 2019 edition of MSSE (3). The authors point out in their literature review that previous nap studies suffer from poor control of confounding factors that may influence the effect of a nap, such as quality of prior sleep, sleep architecture, and when the nap occurs. Therefore, they attempted to tightly control these factors in their study design. Athletic performance is a function of both physical and cognitive prowess, both of which can be influenced by sleep quality. The experimental outcomes for this study included cognitive performance tasks and physical assessments including a complex Karate Specific Test (KST). Karate is a complex interactive sport that requires rapid reactive decision making in addition to strength, speed, and technique. The cognitive performance tasks, Simple Reaction Time, Mental Rotation Test, and Lower Reaction Time, measured how long it took the athlete to jump in response to an audio prompt. Physical assessment tests were a Squat Jump (SJ) and a Countermovement Jump (CMJ) as well as the KST. Subjects also were asked to rate their subjective alertness and fatigue before and after a nap on a Visual Analog Scale. The study design was a 2 × 2 crossover design, with the independent variables of nap or no nap and preceding night of restful night (RN) sleep or partial sleep deprivation (PSD). The day after the monitored sleep night, the subjects engaged in a 30-minute afternoon nap or quiet awake time 30 minutes prior to the cognitive and physical assessments. Therefore, each subject engaged in four protocol conditions, each separated by at least a week: RN + nap, RN + no nap, PSD + nap, PSD + no nap. The sleep the night before testing was closely monitored to ensure that subjects’ sleep patterns were typical. Subjects slept for at least 7 hours during the RN. In the PSD condition, they were awakened after 4 hours of sleep and kept awake doing quiet activities (e.g., watching TV, computer activities, listening to music, reading). Thirteen national level karate athletes (average age 23 ± 2 years) participated in the study. Subjectively, the subjects indicated decreased alertness and increased fatigue after PSD that was only slightly improved after a nap. The nap improved alertness but did not affect fatigue feelings in the RN condition. The PSD had a significant detrimental effect on the cognitive tests that was almost completely alleviated by a preceding nap. The PSD and nap (or no nap) did not affect the physical tasks (SJ and CMJ). However, performance on the more complex KST test was significantly reduced by the PSD in the no nap condition but not the nap condition. The very tightly controlled design of the study makes the findings even more convincing. However, this tight control may decrease its generalizability. The subjects were all young men with well-established sleep patterns and habitual nap-takers. The impact of a nap on athletes with poorer sleep hygiene or who do not normally take naps may be different. Bottom Line: In young high-level karate athletes, a 30-minute nap alleviated the detrimental effects of disrupted sleep on cognitive tasks and complex athletic performance. Disrupted sleep with or without a nap did not affect the performance of simple physical tasks.

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