Biomedical subjects

John N Howell

Publications and source records attributed to John N Howell.

4 recordsLinked to original sources

PubMed2006

Stretch reflex and Hoffmann reflex responses to osteopathic manipulative treatment in subjects with Achilles tendinitis.

CONTEXT: Irvin M. Korr, PhD, hypothesized that sensitivity of the monosynaptic stretch reflex (ie, deep tendon reflex) plays a major role in the restriction-of-motion characteristic of somatic dysfunction, and that restoration of range of motion through osteopathic manipulative treatment (OMT) could be achieved by resetting of the stretch receptor gain. OBJECTIVE: To test Korr's hypothesis in the context of Achilles tendinitis, examining whether OMT applied to patients with Achilles tendinitis reduces the strength of the stretch reflex. METHODS: Subjects were recruited through public advertisements and referrals from healthcare professionals. There were no recruitment restrictions based on demographic factors. Amplitudes for stretch reflex and H-reflex (Hoffmann reflex) in the triceps surae muscles (the soleus together with the lateral and medial heads of the gastrocnemius) were measured in subjects with diagnosed Achilles tendonitis (n=16), both before and after OMT. These measurements were also made in asymptomatic control subjects (n=15) before and after sham manipulative treatment. RESULTS: As predicated on the concepts of the strain-counterstrain model developed by Lawrence H. Jones, DO, the use of OMT produced a 23.1% decrease in the amplitude of the stretch reflex of the soleus (P<.05) in subjects with Achilles tendinitis. Similarly significant responses were measured in the lateral and medial heads of the gastrocnemius in OMT subjects. The H-reflex was not significantly affected by OMT. In control subjects, neither reflex was significantly affected by sham manipulative treatment. By using a rating scale on questionnaires before treatment and daily for 7 days posttreatment, OMT subjects indicated significant clinical improvement in soreness, stiffness, and swelling. CONCLUSION: The reduction of stretch reflex amplitude with OMT, together with no change in H-reflex amplitude, is consistent with Korr's proprioceptive hypothesis for somatic dysfunction and patient treatment. Because subjects' soreness ratings also declined immediately after treatment, decreased nociceptor activity may play an additional role in somatic dysfunction, perhaps by altering stretch reflex amplitude.

Achilles Tendon↗

PubMed2006

Effect of counterstrain on stretch reflexes, hoffmann reflexes, and clinical outcomes in subjects with plantar fasciitis.

CONTEXT: Previous research indicates that osteopathic manipulative treatment based on counterstrain produces a decrease in the stretch reflex of the calf muscles in subjects with Achilles tendinitis. OBJECTIVES: To study the effects of counterstrain on stretch reflex activity and clinical outcomes in subjects with plantar fasciitis. METHODS: In a single-blind, randomized controlled trial of crossover design, the effects of counterstrain were compared with those of placebo in adult subjects (N=20) with plantar fasciitis. The subjects were led to believe that both the counterstrain and placebo were therapeutic modalities whose effects were being compared. Ten subjects (50%) were assigned to receive 3 weeks of counterstrain treatment during phase 1 of the trial, while the other 10 subjects were given placebo capsules. After a 2- to 4-week washout period, phase 2 of the trial began with the interventions reversed. Clinical outcomes were assessed with daily questionnaires. Stretch reflex and H-reflex (Hoffmann reflex) in the calf muscles were assessed twice during each laboratory visit, before and after treatment in the counterstrain phase. RESULTS: No significant changes in the electrically recorded reflexes of the calf muscles were observed in response to treatment. However, changes in the mechanical characteristics of the twitches resulting from the electrical responses were observed. Peak force and time to reach peak force both increased (P< or =.05) in the posttreatment measurements, with the increase being significantly more pronounced in the counterstrain phase (P< .05). A comparison of pretreatment and posttreatment symptom severity demonstrated significant relief of symptoms that was most pronounced immediately following treatment and lasted for 48 hours. CONCLUSIONS: Clinical improvement occurs in subjects with plantar fasciitis in response to counterstrain treatment. The clinical response is accompanied by mechanical, but not electrical, changes in the reflex responses of the calf muscles. The causative relation between the mechanical changes and the clinical responses remains to be explored.

Adult↗

PubMed2002

The "iliacus test": new information for the evaluation of hip extension dysfunction.

This study confirms the clinical value of investigating the "iliacus complex" during evaluations of the low back. A new "iliacus test" isolates this iliacus complex component of limited hip extension. Designed for a single joint, the test isolates motion across the hip joint. Study results include the following: (1) in a comparison with the clinical standard, the Thomas test, data show that the two tests are significantly different in an asymptomatic population between the ages of 18 and 35 years; (2) with the exception of the standard Thomas test, the data show no statistical differences in range of motion when comparing the left side with the right side; (3) examiner-added, end-range pressure for assessment of range of motion when compared with the standard gravity-dependent end range of motion used in the Thomas test yields valuable new information; and (4) data provide a basis for population norms for each test--Thomas and iliacus--in gravity-dependent and examiner-produced tissue-feel end ranges.

Adult↗

PubMed1997

The relationship between elbow flexor volume and angular stiffness at the elbow.

OBJECTIVE: The purpose of this experiment was to determine if a correlation exists between the volume of the elbow flexors and angular stiffness at the elbow, and to determine the contribution of the biceps brachii and the brachialis muscles to angular stiffness. DESIGN: This study is a descriptive, correlational study and presents a graphical model of the passive properties of muscle. BACKGROUND: The correlation between arm volume and angular stiffness has been shown, but the measurement of arm volume was not specific to the structures being strained. Pre-positioning a bi-articular muscle by stretching over one joint decreases the range of motion at the other joint and may affect the stiffness. METHODS: Angular stiffness at the elbow of 14 female and 15 male volunteers was measured, and the volume of the elbow flexors was calculated from compounded ultrasound imaging. Initial biceps length was set by pre-positioning the shoulder in two different positions. RESULTS: A significant linear relationship was observed between the slope of phase 1 of the stiffness curve and volume of the elbow flexors in both horizontal flexion (r = 0.92) and horizontal extension (r = 0.79) of the shoulder. Phase 2 of the stiffness curve showed no linear relationship to muscle volume in either shoulder position (flexion, r = 0.22; extension r = 0.33). The slopes of phases 1 and 2 were significantly greater with the shoulder in horizontal extension than in horizontal flexion. CONCLUSION: The volume of the elbow flexor muscles is a good predictor of angular stiffness in phase 1 of the curve. A model of the additive contribution of the biceps and brachialis muscles is presented to account for the increased stiffness in the shoulder extended position. RELEVANCE: Recognition of the correlation between muscle volume and stiffness, coupled with understanding that pre-positioning a bi-articular muscle may affect muscle stiffness may aid the clinician in accurately assessing muscle stiffness in patients with connective tissue disorders, neurological dysfunction and contractures.

Journal Article↗