James C. Agre

Neuromuscular adaptations to concurrent strength and endurance training

PURPOSE The purpose of this study was to examine muscle morphological and neural activation adaptations resulting from the interaction between concurrent strength and endurance training. METHODS Thirty sedentary healthy male subjects were randomly assigned to one of three training groups that performed 10 wk of 3-d x wk(-1) high-intensity strength training (S), cycle endurance training (E), or concurrent strength and endurance training (CC). Strength, quadriceps-muscle biopsies, computed tomography scans at mid-thigh, and surface electromyogram (EMG) assessments were made before and after training. RESULTS S and CC groups demonstrated similar increases (P < 0.0001) in both thigh extensor (12 and 14%) and flexor/adductor (7 and 6%) muscle areas. Type II myofiber areas similarly increased (P < 0.002) in both S (24%) and CC (28%) groups, whereas the increase (P < 0.004) in Type I area with S training (19%) was also similar to the nonsignificant (P = 0.041) increase with CC training (13%). Significant increases (P < 0.005) in maximal isometric knee-extension torque were accompanied by nonsignificant (P <or= 0.07) increases in root mean squared EMG amplitude of the quadriceps musculature for both S and C groups. No changes (P > 0.38) in the EMG/torque relation across 20 to 100% maximal voluntary contractions occurred in any group. A small 3% increase (P < 0.01) in thigh extensor area was the only change in any of the above variables with E training. CONCLUSIONS Findings indicate 3-d x wk(-1) concurrent performance of both strength and endurance training does not impair adaptations in strength, muscle hypertrophy, and neural activation induced by strength training alone. Results provide a physiological basis to support several performance studies that consistently indicate 3-d x wk(-1) concurrent training does not impair strength development over the short term.

Hamstring injuries. Proposed aetiological factors, prevention, and treatment.

SummaryInjuries to the hamstring muscles can be devastating to the athlete because these injuries frequently heal slowly and have a tendency to recur. It is thought that many of the recurrent injuries to the hamstring musculotendinous unit are the result of inadequate rehabilitation following the initial injury. The severity of hamstring injuries is usually of first or second degree, but occasionally third-degree injuries (complete rupture of the musculotendinous unit) do occur.Most hamstring strain injuries occur while running or sprinting. Several aetiological factors have been proposed as being related to injury of the hamstring musculotendinous unit. They include: poor flexibility, inadequate muscle strength and/or endurance, dyssynergic muscle contraction during running, insufficient warm-up and stretching prior to exercise, awkward running style, and a return to activity before complete rehabilitation following injury.Treatment for hamstring injuries includes rest and immobilisation immediately following injury and then a gradually increasing programme of mobilisation, strengthening, and activity. Permission to return to athletic competition should be withheld until full rehabilitation has been achieved (complete return of muscle strength, endurance, and flexibility in addition to a return of co-ordination and athletic agility). Failure to achieve full rehabilitation will only predispose the athlete to recurrent injury. The best treatment for hamstring injuries is prevention, which should include training to maintain and/or improve strength, flexibility, endurance, co-ordination, and agility.

Effect of training on VO2max, thigh strength, and muscle morphology in septuagenarian women

The purpose of this study was to determine the effects of a long-term (50 wk) combined aerobic-resistance training program on maximal oxygen consumption (VO2max, thigh strength, and vastus lateralis fiber morphology in healthy septuagenarian women (mean age = 72 +/- 6 yr). Subjects volunteered to be in either an exercise (Ex; N = 17) or control (Con; N = 10) group. Con subjects were 34% less active in winter than in summer, Ex subjects maintained their summer activity level on exercise days in winter. Initial, intermediate (20 wk), and final (50 wk) measurements were made for isokinetic knee extension/flexion strength; VO2max and morphological measurements from a muscle biopsy were made at the initial and final times only. Both groups gained in leg strength (Ex = +6.5%; Con = +7.8%; P less than or equal to 0.05) during the summer; in the winter the Ex group maintained leg strength and the Con group declined 12.2% (P less than or equal to 0.05). The fast-twitch muscle fiber area (Type IIb) increased 29% (P less than or equal to 0.001) in the Ex group and declined 26% (P = 0.014) in the Con group. VO2max increased only in the Ex group (16%; P less than 0.001). We conclude that healthy septuagenarian women can increase aerobic capacity, leg strength, and Type IIb muscle fiber area with a long-duration, combined aerobic-resistance exercise program.

Strength, endurance, and work capacity after muscle strengthening exercise in postpolio subjects

OBJECTIVE To determine whether a 12-week home quadriceps muscle strengthening exercise program would increase muscle strength, isometric endurance, and tension time index (TTI) in postpolio syndrome subjects without adversely affecting the surviving motor units or the muscle. DESIGN A longitudinal study to investigate the effect of a 12-week exercise program on neuromuscular function and electromyographic variables. SETTING Neuromuscular laboratory of a university hospital. SUBJECTS Seven subjects were recruited from a cohort of 12 subjects who had participated in a previous exercise study. All subjects had greater than antigravity strength of the quadriceps. Upon completion of a postpolio questionnaire, all acknowledged common postpolio syndrome symptoms such as new fatigue, pain, and weakness; 6 of the 7 acknowledged new strength decline. INTERVENTION On Mondays and Thursdays subjects performed three sets of four maximal isometric contractions of the quadriceps held for 5 seconds each. On Tuesdays and Fridays subjects performed three sets of 12 dynamic knee extension exercises with ankle weights. MAIN OUTCOME MEASURES Neuromuscular variables of the quadriceps muscles were measured at the beginning and completion of the exercise program and included: isokinetic peak torque (ISOKPT, at 60 degrees/sec angular velocity) and total work performed of four contractions (ISOKTW), isometric peak torque (MVC), endurance (EDUR, time subject could hold isometric contraction at 40% of the initial MVC), isometric tension time index (TTI, product of endurance time and torque at 40% of MVC), and initial and final ankle weight (WGT, kg) lifted. Electromyographic variables included: fiber density (FD), jitter (MCD), and blocking (BLK) from single fiber assessment and median macro amplitude (MACRO). Serum creatine kinase (CK) was also measured initially and at 4-week intervals throughout the study. RESULTS The following variables significantly (p < .05) increased: WGT by 47%, ISOKPT, 15%, ISOKTW, 15%; MVC, 36%; EDUR, 21%; TTI, 18%. The following variables did not significantly (p > .05) change: FD, MCD, BLK, MACRO, and CK. CONCLUSIONS This home exercise program significantly increased strength, endurance, and TTI without apparently adversely affecting the motor units or the muscle, as the EMG and CK variables did not change.

A multicenter, randomized, double-blinded trial of pyridostigmine in postpolio syndrome

To the Editor: Gilbert and Buncher1 use linear information theory2 to analyze selected findings on seizure recurrence in childhood. They conclude that the information regarding recurrence risk contained in the EEG is insufficient to justify its routine use after a first seizure in children. We note several objections. The authors begin with a false premise that the only utility of the EEG is to ascertain recurrence risk. In reality: 1) when the diagnosis is unclear, the EEG may differentiate seizures from other nonepileptic events; 2) the EEG may distinguish a first seizure from epilepsy newly presented to medical attention; e.g., the child with a tonic-clonic seizure whose EEG demonstrates a 3 Hz generalized spike and wave pattern with staring spells. (such children are excluded from the first seizure studies Gilbert and Buncher analyzed); 3) the EEG is critical for syndrome diagnosis; 4) the determination of the syndrome strongly influences use of subsequent neuro-imaging,3 and treatment decisions independent of recurrence risk as demonstrated in a recent French study.4 It also provides crucial information about long-term prognosis; 5) a syndromic diagnosis may influence advice about other restrictions, e.g., photo-sensitivity has implications for exposure to TV, computers, and strobe lights. The paper that Gilbert and Buncher base their analysis clearly states that testing is justified when the results alter treatment or management or provide prognostic information. “Patients may be interested in prognostic information that testing provides even if it is not used to guide treatment.”2 Fundamental to information theory is the notion that the cost of obtaining the additional information must be weighed in light of the value of the information and its intended use. Gilbert and Buncher ignore this fundamental principle that underlies information theory and appear unaware of the clinical process and goals of evaluating children with seizures. They also ignore multivariable analyses in which the EEG is used to differentiate risks of ,20% versus

Late effects of polio: Critical review of the literature on neuromuscular function

75%. By ignoring the value of the EEG in providing information that may influence both management and prognosis and by limiting the value of the EEG to a single parameter (predicting recurrence risk), the authors demonstrate how statistics, untempered by clinical judgment and common sense, can be misleading.

Needle electromyographic evaluation of patients with myofascial or fibromyalgic pain

Many individuals who have had poliomyelitis are now complaining of several new problems attributed to their former illness including muscle atrophy; fatigue; progressive weakness; and muscle, back, and joint pain. This paper critically examines the literature regarding the neuromuscular effects of poliomyelitis. Weakness resulting from poliomyelitis was due to destruction of anterior horn cells. After the illness, muscle strength was partially recovered as a result of several physiologic adaptive mechanisms including terminal sprouting and reinnervation, myofiber hypertrophy, and, possibly, myofiber type transformation. Several pathophysiologic and functional etiologies have been proposed for late neuromuscular deterioration, but none has been proven. In fact, to date, there is no objective evidence documenting progressive loss of strength in polio survivors. Studies attempting to differentiate polio survivors with and without symptoms of deterioration have resulted in conflicting results; however, it appears reasonable to conclude that symptomatic postpolio subjects had a more severe illness with greater loss of neuromuscular function. Exercise may be helpful for many postpolio patients, but the prescription must be tailored to the individual to avoid problems of overuse or excessive fatigue.

Psychologic characteristics of polio survivors: A preliminary report

Several past studies have evaluated the electromyographic activity of myofascial trigger points with conflicting results. This study was performed to determine whether spontaneous activity or motor unit activity was present in patients with focal myofascial pain or fibromyalgia. Using routine needle electromyographic techniques, we sampled reproducibly tender focal areas (tender points), similar tender areas with pain referral (trigger points), associated muscle bands and adjacent uninvolved musculature. Twenty-five subjects (14 females, 11 males, mean ± SD age 43 ± 14 years) were studied; twenty-one subjects with focal myofascial pain and four with fibromyalgia. Spontaneous fibrillatory or positive sharp wave potentials were not found in any muscle in the 25 subjects. There was no evidence of focal motor unit activity in the tender points, trigger points or associated muscle bands in either group. Motor unit recruitment was similar in all areas sampled. We conclude that no electrodiagnostic evidence of ongoing denervation or focal muscle spasm is found in association with focal myofascial pain or fibromyalgia.

Low-intensity, alternate-day exercise improves muscle performance without apparent adverse effect in postpolio patients

Ninety-three men and women with histories of polio were administered the Symptom Check List-90 Revised (SCL-90R), Psychosocial Adjustment to Illness Scale-Self Report (PAIS-SR), and a questionnaire about their polio histories. The SCL-90R and PAIS-SR are measures of emotional and psychosocial functioning. Two samples were used: a clinic sample (n = 71) and a postpolio support group sample (n = 22). Initial results for both on the SCL-90R and PAIS-SR indicated elevated scores on a number of subscales. SCL-90R subscale elevated scores for men included those for somatization, depression, anxiety, hostility, and phobia, whereas for women there were elevations on measures of somatization, depression, anxiety, and psychoticism. Elevations were found in the following subscales on the PAIS-SR (pooling men and women): health care orientation, social environment, and extended family relationships. Men scored slightly, but not significantly, higher than women in the SCL-90R except for the hostility subscale, in which the difference was significant (p less than 0.05). Symptom profiles indicated psychologic distress. Comparisons with variables associated with polio and its late effects (such as severity of initial polio, use of an iron lung during initial illness, number of involved limbs, etc) were not statistically significant.

The Role of Exercise in the Patient with Post-Polio Syndrome

The purpose of this study was to examine the effect of a low-intensity, alternate-day, 12 wk quadriceps muscle-strengthening exercise program on muscle strength and muscle and motor unit integrity in 12 postpolio patients. Patients performed six to ten repetitions of a 5-s duration knee extension exercise with ankle weights. After completing six repetitions, patients rated the perceived exertion (RPE) in the exercised muscle. The patient continued repetitions until RPE was >/= 17 or ten repetitions were performed. The weight was increased the next exercise day whenever the RPE was < 17 after ten repetitions. Before and after the training program, median macroamplitude as well as jitter and blocking were determined electromyographically (EMG), serum creatine kinase (CK) was measured, and quadriceps muscle strength was assessed. The ankle weight lifted after 2 wk of training and at the end of the program were also recorded. Although the ankle weight lifted at the end of the program significantly (P < 0.05) increased from a mean +/- SD of 7.1 +/- 2.7 to 11.2 +/- 4.7 kg, the dynametrically determined muscle strength measures did not significantly (P > 0.05) increase. The EMG and the serum CK variables also did not significantly (P >0.05) change as a result of the exercise program. We conclude that performance was improved, as demonstrated by an increase in the amount of weight the patients lifted in the exercise program. No evidence was found to show that this program adversely affected the motor units or the muscle as the EMG and CK did not change.