Lactic acid has played an important role in the traditional theory of muscle fatigue and limitation of endurance exercise performance. It has been called a waste product of anaerobic metabolism and has been believed to be responsible for the uncomfortable "burn" of intense exercise and directly responsible for the metabolic acidosis of exercise, leading to decreased muscle contractility and ultimately cessation of exercise. Although this premise has been commonly taught, it is not supported by the scientific literature and has led to a great deal of confusion among the sports medicine and exercise science communities. This review will provide the sports medicine clinician with an understanding of contemporary lactate theories, including lactate's role in energy production, its contributions to metabolic acidosis, and its function as an energy substrate for a variety of tissues. Lactate threshold concepts will also be discussed, including a practical approach to understanding prediction of performance and monitoring of training progress based on these parameters.

Pelvic stress fractures are rare and present unique challenges for medical personnel. Delayed healing can lead to increased physical, psychological, and social stress for athletes. Recent literature suggests effective use of a synthetic derivative of parathyroid hormone, teriparatide, to augment healing of delayed-union stress fractures. We present a case of a female National Collegiate Athletic Association Division I gymnast successfully returned to play after a 12-week course of teriparatide injections for an ischioacetabular stress fracture.

Tenosynovial (extra-articular) chondromatosis (TC) is a condition characterized by the cartilaginous proliferation of synovial cells derived from the synovial lining of bursa and tendon sheaths. These lesions are often multinodular and most commonly present with complaints of swelling or pain. Treatment of TC primarily entails surgical excision. There are no known reports of TC in collegiate athletes. We present a case of TC in a Division I tennis player.

IntroductionDistal forearm fractures (DFF) account for 1.5% of emergency department (ED) visits in the United States. Clinicians frequently obtain imaging above/below the location of injury to rule out additional injuries. We sought to determine the incidence of associated proximal fractures (APF) in the setting of DFF and to evaluate the imaging practices in a nationally representative sample of EDs.MethodsWe queried the 2013 National Emergency Department Sample using International Classification of Diseases, 9th edition, diagnostic codes for DFF and APF. Current Procedural Technology codes identified associated imaging studies. We calculated national estimates using a weighted analysis of patient and hospital-level characteristics associated with APF and imaging practices. An analysis of costs estimated the financial impact of additional imaging in patients with DFF using Medicare reimbursement to approximate costs according to the 2018 Medicare Physician Fee Schedule.ResultsIn 2013, an estimated 297,755 ED visits (weighted) were associated with a DFF, of which 1.6% (4836 cases) had an APF. The incidence of APF was lower among females (odds ratio [OR] (0.76); 95% confidence interval [CI], 0.64–0.91) but higher in metropolitan teaching hospitals compared to metropolitan non-teaching hospitals (OR [2.39]; 95% CI, 1.43–3.99) and Level 1 trauma centers (OR [3.9]; 95%, 1.91–7.96) compared to non-trauma centers. Approximately 40% (n = 117,948) of those with only DFF received non-wrist radiographs and 19% (n = 55,236) underwent non-wrist/non-forearm imaging. Factors independently associated with additional imaging included gender, payer, patient and hospital rurality, hospital region, teaching status, ownership, and trauma center level. Nearly $3.6 million (2018 U.S. dollars) was spent on the aforementioned additional imaging.ConclusionDespite the frequency of proximal imaging in patients with DFF, the incidence of APF was low. Further study to identify risk factors for APF based on mechanism and physical examination factors may result in reduced imaging and decreased avoidable healthcare spending.

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