Composition of the mount st. Helens ashfall in the moscow-pullman area on 18 may 1980.

Mineralogical and chemical analyses of the ashfall from Mount St. Helens on 18 May 1980 indicate that there were two distinct ashes. The early dark ash is composed principally of plagioclase and lithic fragments of plagioclase and glass with titanium-rich magnetite and some basaltic hornblende and orthopyroxene. The later pale ash, four-fifths by weight of the whole fallout, is 80 percent glass with plagioclase as the principal crystalline phase. Quartz and potassium feldspar are rare to absent in both ashes. Chemical analyses of nine ash fractions and of the glass in each type emphasize the differences between the two ash types and their chemical homogeneity.

Snow skiing for the physically disabled.

The sport of snow skiing by the physically disabled, which originated in Europe in 1935 and first received attention in the United States in the 1940s, is reviewed in terms of opportunities available, instructions, adaptive equipment necessary, and benefits provided. Persons with a wide variety of disabilities (such as cerebral palsy, multiple sclerosis, spinal cord injury, hemiplegia, amputation, blindness, spina bifida, and muscular dystrophy) can participate. Accordingly, a wide range of adaptive equipment is available--including outrigger skis, flip-skis, canting wedges, ski bras, "toe spreaders," sit-skis, and mono-skis--to allow safe enjoyment of the sport. Programs for instruction of the disabled skier are increasing in number and popularity, and numerous opportunities are available to enter competitive events sponsored by National Handicapped Sports. Both the participants and the instructors relate the numerous physical and psychologic benefits that can be derived from skiing; the sport provides an almost universal enjoyment of the sense of freedom and independence. Snow skiing is an enjoyable, beneficial, outdoor cold-weather activity that the disabled population can safely learn with proper instruction.

The preparticipation physical examination: Mayo Clinic experience with 2,739 examinations.

OBJECTIVE: To report the results of preparticipation physical examination (PPE) performed on 2,739 high school athletes and present a model for providing PPEs in similar practice settings. DESIGN: We analyzed 2,739 PPEs performed on high school athletes by means of a station examination approach in our Sports Medicine Center during a 3-year period. MATERIAL AND METHODS: Personnel from the Departments of Physical Medicine and Rehabilitation, Orthopedics, Family Medicine, and Internal Medicine participated in performance of a comprehensive station-based physical examination of high school athletes. The final reviewing physician assigned one of three dispositions to each athlete: cleared for participation in sports, not cleared, or cleared with follow-up recommended. RESULTS: On the basis of PPE findings, 53 athletes (1.9%) were disqualified from participation in sports. Abnormalities that did not preclude participation but necessitated follow-up were identified in another 327 athletes (11.9%). Musculoskeletal problems were the leading cause of restriction from sports activities (43.4%) and the second leading cause for recommended follow-up (27.8%). Clinically significant cardiac abnormalities were noted in only 10 athletes (0.37% of the overall group of students). Our methods and results are discussed in relationship to previous PPE studies. CONCLUSION: On the basis of this study, we conclude that (1) a Sports Medicine Clinic can efficiently administer PPEs to a large number of athletes by using an adaptable station approach, (2) the musculoskeletal component of a PPE is an important part of the process that often reveals abnormalities and should be performed by qualified personnel, and (3) each practice must refine its delivery of PPEs on the basis of its particular environment.

Thigh injuries in athletes.

The thigh, which consists of the heavily muscled region around the femur, is vulnerable to many types of athletic injury. This review addresses the assessment, prevention, and rehabilitation of both the common thigh injuries associated with participation in sports, such as contusions and myositis ossificans traumatica, and a few relatively uncommon but diagnostically important entities that sports physicians must recognize when an athlete has pain or dysfunction attributable to the thigh. Dividing the thigh into anatomic compartments aids in both differential diagnosis and understanding of the pathomechanics that lead to injury. Rehabilitation is especially emphasized because improper selection of modalities or misuse of exercise can seriously impede or worsen recovery. Conversely, the use of appropriate rehabilitation principles and new concepts in exercise prescription can decrease morbidity and lead to rapid resumption of sports.

Effect of corrective rearfoot orthotic devices on ground reaction forces during ambulation.

OBJECTIVE: To determine the quantitative effects of a corrective rearfoot orthotic device on the vertical, anteroposterior, and mediolateral ground reaction forces (GRFs) during ambulation. DESIGN: We conducted a prospective, randomized, single-blinded study of 25 subjects during ambulation with and without a rearfoot orthotic device. MATERIAL AND METHODS: Thirteen men and 12 women were enrolled in the study; the inclusion criteria included asymptomatic pes planus (5 to 10 degrees of calcaneal eversion). Each subject walked across a standard force plate in 10 trials without an orthotic device. The force plate was used to quantify the effect of a semirigid functional rearfoot orthotic device on GRFs and the center of pressure versus a standard shoe with no device. The observer was blinded, trials were completed in random order, and the paired t test was used for statistical analysis. RESULTS: No evidence suggested the presence of a significant difference in mediolateral GRFs and in the center of pressure exerted at 10%, 20%, 50%, and 80% of stance phase with and without the orthotic device. Significant reductions were noted in vertical GRFs per newton of body weight exerted at 10% (P = 0.0009) and 20% (P = 0.0383) of stance phase and in anteroposterior GRFs exerted at 10% (P = 0.0009) and 50% (P = 0.0033) of stance phase when ambulation was compared with and without the orthotic device. CONCLUSION: These results indicate that a rearfoot orthotic device reduces vertical and anteroposterior GRFs in the early stages of the stance phase during the gait cycle. We found no evidence to suggest a significant difference at any of the percent stance phases when comparisons were made of mediolateral GRFs exerted with and without the orthotic device. These data are contrary to current hypotheses about use of orthotic devices, and further studies would be helpful to reproduce these findings and to determine whether these changes are related to clinical improvement in symptomatic pes planus.

Medical coverage for multievent sports competition: a comprehensive analysis of injuries in the 1994 Star of the North Summer Games.

OBJECTIVE: To determine the incidence and type of requests for medical assistance and the treatment required in 21 sports at the 1994 Star of the North Summer Games and to develop a plan, based on these findings, for efficient allocation of medical supplies and staff. DESIGN: We reviewed our experience with a large multisport amateur athletic event and analyzed the pattern of injuries for participants in the various sports. MATERIAL AND METHODS: Injury evaluation forms and medical supply kits were given to the health-care volunteers, who received preliminary instructions on classifications and definitions of injuries and on appropriate completion of the forms. When a medical contact occurred, an evaluation form was completed. The data from these forms were subsequently compiled and analyzed. RESULTS: Of 6,243 athletes who participated in the 1994 Star of the North Summer Games, 55 (0.88%) received medical attention (2 officials also required medical assistance). The sports with the greatest number of medical contacts were soccer and track and field--31 and 16 contacts for medical assistance, respectively. The lower extremities were the anatomic site most frequently involved in injury (62% of the medical contacts). The most common types of injury were contusions, strains, and sprains. CONCLUSION: Because few injuries were sustained and most were of minor severity, basic medical supplies (such as ice bags and compression wraps) were sufficient. For locations with a scarcity of medical personnel, a triage system can be established in which athletic trainers or registered nurses manage the initial assessments and refer cases, as needed, to physicians for specialized care. An effective communication system can also considerably reduce volunteer hours.

Psychologic, situational, and physiologic variables and on-ice performance of youth hockey goalkeepers.

OBJECTIVE: To determine the relationship between psychologic, situational, and physiologic variables and on-ice performance of youth hockey goalkeepers. DESIGN: This study was structured to identify relationships and predictors of goalie performance. MATERIAL AND METHODS: Because athletes playing solo positions in team sports have not been analyzed in depth in terms of precompetition anxiety and because goalkeeper performance is critical to game outcome, we undertook a study of 43 goalies at a hockey camp. These goalies completed psychometric inventories to assess trait and state anxiety, confidence, life stress, and social support. Holter monitors measured heart rate while the goalies rotated through on-ice stations. Goalies were videotaped at the puck-shooting machine station, and performance (percent saves) was calculated. RESULTS: Trait (somatic) anxiety and positive mood state (ability to share) had different but significant relationships with on-ice performance. Heart rates ranged from 88 to 208 beats/min at the on-ice stations. Mean heart rate for older goalies (14 to 18 years of age) was 164 beats/min at the puck-shooting machine and 176 beats/min at other stations such as the slap-shot station. CONCLUSION: Older goalies performed well at a high level of arousal. Better performing goalies were more experienced, had faster heart rates "in the net," and had lower scores on all measures of anxiety.

A preliminary analysis of psychophysiological variables and nursing performance in situations of increasing criticality.

OBJECTIVE: To examine the relationship between psychological, physiological, and performance variables in intensive care unit (ICU) nurses in situations of increasing criticality. SUBJECTS AND METHODS: Psychophysiological variables and endotracheal suctioning performance were examined in a classroom, a skills laboratory, and an ICU. Situation-specific anxiety (state anxiety) and the predisposition to view situations as threatening (trait anxiety), cognitive appraisal, and heart rate were measured and compared with self-appraisal and a nurse instructor's ratings of suctioning performance. Baseline data were obtained during class on 45 novice ICU nurses. RESULTS: Twenty-six nurses provided complete data, which included being videotaped and monitored in the classroom, in the skills laboratory performing endotracheal suctioning, and in the ICU during suctioning. High state anxiety significantly predicted poor ICU suctioning performance (P<.04). Nurses high in state and trait anxiety, worry, and heart rate performed poorly compared with less anxious nurses. Nurses in this study who performed best had a mean heart rate of 94 beats/min. CONCLUSION: Those nurses who are high state anxious, high trait anxious, and worried and who had a faster heart rate performed less well than their more relaxed peers. Nurses with high state anxiety may be at risk for attrition, burnout, medical errors, and poor performance in other ICU nursing tasks.

A multidisciplinary study of the 'yips' phenomenon in golf: An exploratory analysis.

BACKGROUND: The 'yips' is a psychoneuromuscular impediment affecting execution of the putting stroke in golf. Yips symptoms of jerks, tremors and freezing often occur during tournament golf and may cause performance problems. Yips-affected golfers add approximately 4.7 strokes to their scores for 18 holes of golf, and have more forearm electromyogram activity and higher competitive anxiety than nonaffected golfers in both high and low anxiety putting conditions. The aetiology of the yips is not clear. OBJECTIVE: To determine whether the yips is a neurological problem exacerbated by anxiety, or whether the behaviour is initiated by anxiety and results in a permanent neuromuscular impediment. METHODS: In phase I, golf professionals assisted investigators in developing a yips questionnaire that was sent to tournament players (<12 handicap) to establish the prevalence and characteristics of the yips. Phase II measured putting behaviour in scenarios that contribute to the yips response. Four self-reported yips and 3 nonaffected golfers putted 3 scenarios using an uncorrected grip and a standard length putter. Heart rate was superimposed on the videotape and the putter grip was instrumented with strain gauges to measure grip force. Electromyograms and relative putting performance were also measured. RESULTS: The questionnaire was sent to 2,630 tournament players, of whom 1,031 (39%) responded (986 men and 45 women). Of these, 541 (52%) perceived they experienced the yips compared with 490 (48%) who did not. Yips-affected golfers reported that the most troublesome putts were 3, 4 and 2 feet (0.9, 1.2 and 0.6 metres) from the hole. Fast, downhill, left-to-right breaking putts and tournament play also elicited the yips response. Golfers affected by the yips had a faster mean heart rate, increased electromyogram activity patterns and exerted more grip force than nonrffected golfers and had a poorer putting performance. CONCLUSIONS: For <10 handicap male golfers and <12 handicap female golfers, the prevalence of the yips is between 32.5% and 47.7%, a high proportion of serious golfers. This high prevalence suggests that medical practitioners need to understand the aetiology of the yips phenomenon so that interventions can be identified and tested for effectiveness in alleviating symptoms. Although previous investigators concluded that the yips is a neuromuscular impediment aggravated but not caused by anxiety, we believe the yips represents a continuum on which 'choking' (anxiety-related) and dystonia symptoms anchor the extremes. The aetiology may well be an interaction of psychoneuromuscular influences. Future research to test the effect of medications such as beta-blockers should assist in better identifying the contributions these factors make to the yips phenomenon.

Differences in repositioning error among patients with low back pain compared with control subjects.

STUDY DESIGN: Trunk repositioning error was measured in 20 patients with chronic low back pain and 20 control subjects. OBJECTIVES: To measure trunk repositioning error as a method of measuring proprioception of the low back and to compare trunk repositioning error in patients with low back pain and in control subjects. SUMMARY OF BACKGROUND DATA: Although many current low back pain rehabilitation programs incorporate proprioceptive training, very little research has been performed on proprioception of the low back. METHODS: While standing with the legs and pelvis immobilized, the subject bent the trunk to a predetermined target position and then attempted to replicate the position. Repositioning error was calculated as the absolute difference between the actual target position and the subject-perceived target position. The multiple target positions in the frontal and sagittal planes were tested. Trunk position was measured with a 3Space Tracker, which analyzes the three-dimensional position of the body. RESULTS: Repositioning error in patients with low back pain was significantly higher than that of control subjects in flexion, and significantly lower than that of control subjects in extension. CONCLUSIONS: The increase in repositioning error of patients with low back pain during flexion implies that some aspects of proprioception are lost in patients with low back pain. The decrease in repositioning error in patients with low back pain in extension is not as easily explained, but could possibly be caused by increased activation of mechanoreceptors in facet joints.

Repositioning error in low back pain. Comparing trunk repositioning error in subjects with chronic low back pain and control subjects.

STUDY DESIGN: Repositioning error of the trunk was tested in 20 subjects with chronic low back pain and in 20 control subjects. The 3Space Tracker (Polhemus, Colchester, VT), a device that measures three-dimensional position in space, was used to determine the subject's trunk position. OBJECTIVES: To determine whether repositioning error is different in subjects with chronic low back pain than in control subjects. SUMMARY OF BACKGROUND DATA: Proprioception allows the body to maintain proper orientation during static and dynamic activities. In peripheral joint injuries, researchers have demonstrated a loss of some aspects of proprioception and improvement in outcome with retraining. Although the components of proprioception in subjects with low back pain have not been well studied, it is thought that these persons lose some elements of proprioception that can be measured in a quantifiable way. If so, then rehabilitation to improve these deficits is important. In this pilot study, one aspect of proprioception, repositioning error, was examined. METHODS: The subjects attempted to replicate target positions of the trunk in flexion, extension, lateral bending, and lateral rotation. Repositioning error was calculated as the absolute difference between the actual and the subject-replicated target positions. RESULTS: No significant difference was found in repositioning error between the control subjects and the persons with chronic low back pain. CONCLUSIONS: Because proprioception is complex and entails the use of many afferent receptors, it is difficult to measure any one afferent deficiency discretely. The authors believe that this study, in which one aspect of proprioception was measured in an indirect manner, provides important background information on low back position sense. Further studies analyzing aspects of proprioception in subjects with low back pain are recommended.

Snow skiing injuries in physically disabled skiers.

This study, through retrospective review, examines the injury rate of selected disable skiing populations in general and as compared to able-bodied skiers in areas where comparison was possible. Data on disabled skiers gathered from instructional programs at multiple sites indicate that the disabled skier had a very low rate of injury occurrence. Where comparison could be make, it was found that there was no significant difference in overall injury rates between able-bodied and physically disabled skiers. Disabled skiers appear to sustain less severe injuries, and they do not show the trend in increasing injury rates that able-bodied skiers in this study show. In addition, the uphill transport of skiers with a disability who use sit- or mono-skis was examined in one large program and found to be efficient and exceedingly safe, with no injuries reported. A major limitation of this study is the inconsistency in methods of data collection and reporting. There is a need for further prospective studies in the general able-bodied and disabled skiing populations with direct comparisons of rate, location and severity of injury, type of disability, and experience level of the skier. We hope that this study will stimulate more ski areas to allow disabled skiers on their slopes, even it limited to participation in supervised, instructional programs.

Ankle disk training influences reaction times of selected muscles in a simulated ankle sprain.

Ankle disk training has been used as an exercise in sports medicine clinics to help protect against ankle sprains. This study investigated the effects of ankle disk training on the contraction pattern of the anterior tibialis, posterior tibialis, peroneus longus, and flexor digitorum longus muscles in a simulated ankle sprain. Twenty adults were recruited and divided into a control group and an experimental group. A platform with a trapdoor was used to simulate a lateral ankle sprain. Electromyographic data were recorded from each subject in pretraining and posttraining tests. The experimental group underwent ankle disk training for 8 weeks between the pretraining and posttraining tests. In the pretraining test, the four muscles started to contract simultaneously; in the posttraining test, the contractions of the anterior and posterior tibialis muscles were delayed. This delay favors the correction of excessive ankle inversion. This study examined the effects of one form of proprioceptive training on muscle reaction times, and its results may explain why such training can help protect against ankle sprains.

An eccentric- and concentric-strength profile of shoulder external and internal rotator muscles in professional baseball pitchers.

The purpose of this study was to establish a data base on the isokinetic eccentric muscular performance characteristics of external and internal rotator muscles in the shoulders of professional baseball pitchers. Concentric data are also included and compared with previously published concentric studies. Twenty-five professional baseball pitchers were evaluated with a Kin-Com isokinetic dynamometer. The subjects tested had a mean age of 23.5 years and a mean body weight of 199 pounds. Eccentric and concentric isokinetic tests were performed at 60 and 120 deg/sec. The testing protocol was standardized for each subject. Test results indicated no statistically significant difference in mean torque between throwing and nonthrowing shoulders for either external or internal rotator muscle groups. Eccentric strength was significantly greater than concentric strength for all muscle groups tested. The external-to-internal rotator muscle strength ratios were well above those previously published for high school through professional pitchers. Mean torque-to-lean body weight ratios were also included to establish a data base. This study establishes one of the first data bases for eccentric isokinetic muscle strength of shoulder rotator muscles in professional baseball pitchers. The data may help clinicians prevent and rehabilitate shoulder injuries in professional throwing athletes.

The effect of ankle disk training on muscle reaction time in subjects with a history of ankle sprain.

The purpose of this study was to determine whether 8 weeks of ankle disk training alters ankle muscle onset latency of patients with a history of lateral ankle sprain. The training was completed by eight minimally symptomatic subjects with a history of nonrehabilitated, unilateral, inversion ankle sprain sustained between 6 and 16 months before entry into the study. Ankle inversion perturbations monitored by fine-wire electromyography were performed in four lower extremity muscles (anterior tibialis, posterior tibialis, peroneus longus, and flexor digitorum longus) of all subjects on both the injured (experimental) and noninjured (control) legs. Testing was performed at study entry and after 8 weeks of ankle disk training on the previously injured ankle. Results revealed a statistically significant decrease in the anterior tibialis onset latency in both the experimental (67.6 +/- 20.3 to 51.7 +/- 17.6) and control (65.5 +/- 9.8 to 53.8 +/- 23.7) ankles after the training period. These findings indicate that muscle onset latency decreases in specific ankle muscle groups after ankle disk training in previously injured ankles. Both the experimental and control ankles demonstrated a significant change, which raises the question as to whether a proprioceptive cross-training effect occurred.

A valid and reliable method for measuring the kicking accuracy of soccer players.

Kicking accuracy is an important component of soccer performance. We constructed a plywood target measuring 243.5cm wide x 122cm high. Carbon paper applied to the surface of the target allowed measurement by 2 raters from a bull's-eye to 10 ball marks left by kicks. Intraclass correlation coefficients with 95% confidence intervals were used to determine the intra- and interrater reliability of the measurement to each ball mark. Mean and median distances from bulls-eye to ball mark were 89.9cm and 97.9cm, respectively (range, 25.7 to 150.75cm). The intraclass correlation coefficients for intra- and interrater reliability were 0.99. The root mean square error of measurement indicated that accuracy of measurement was within 0.15cm. These results suggest that our method of assessing kicking accuracy is a valid and reliable tool for analysing performance. Because this tool closely replicates kicking into a soccer goal, we feel that it also has validity. To our knowledge, no other tool or measure (e.g.. number of shots on goal or number of goals per game) has comparable validity and reliability. This method can be used as a training tool and for future investigations of kicking accuracy.

Snow skiing.

There are many inherent difficulties in the collection of epidemiologic ski data, but important trends have been identified. Further investigation into controllable risk factors is currently in progress in an attempt to reduce injury incidence, along with prophylactic strength training and conditioning programs. A comprehensive ski-specific training program entailing training of the energy systems, isolated and kinetic chain strength training, skill-specific training, and psychological training is essential to ensure the optimal performance and safety of the skier. Rehabilitation issues also can be addressed in the context of the above elements.

Proprioception.

Although definitions of proprioception may vary, its importance in preventing and rehabilitating athletic injuries remains constant. Proprioception plays a significant role in the afferent-efferent neuromuscular control arc. This control arc is disrupted with joint and soft tissue injury. Restoring proprioception after injury allows the body to maintain stability and orientation during static and dynamic activities. By focusing on aspects of neuromuscular function, such as dynamic joint stability, practitioners can design and study interventions to maximize sport and daily life neuromuscular function. Further research is necessary to elucidate how proprioceptive deficits can be remedied or compensated to improve function and prevent reinjury.

Weight training injuries: part 1: diagnosing and managing acute conditions.

When patients present with acute weight training injuries, familiarity with the demands of the activity can help physicians get the most out of the patient history. Probable risk factors for injury include errors in technique (described in a sidebar), skeletal immaturity, and anabolic steroid abuse. Common acute injuries in weight training include sprains, strains, tendon avulsions, and compartment syndrome. Possible nonmusculoskeletal problems include retinal hemorrhage, radiculopathy, and various cardiovascular complications. Treatment of acute musculoskeletal injuries varies, but usually includes sports medicine mainstays such as prompt RICE. Chronic weight training injuries will be described in part 2 of this series.

Weight training injuries: part 2: diagnosing and managing chronic conditions.

The repetitive nature of weight training and the often heavy loads involved provide fertile ground for chronic injuries. Common chronic injuries include rotator cuff tendinopathy and stress injuries to the vertebrae, clavicles, and upper extremities. In addition, muscle hypertrophy, poor technique, or overuse can contribute to nerve injuries such as thoracic outlet syndrome or suprascapular neuropathy. Chronic medical conditions that are known to occur in weight trainers include vascular stenosis and weight lifter's cephalgia. Management of chronic problems will vary by condition, but relative rest and correction of poor technique are important for many.