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Mark A. Hoffman

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Brent C. Mangus, Laura A. Hoffman, Mark A. Hoffman and Peter Altenburger

Context:

Knowledge and understanding of the principles and applications of joint-mobilization techniques are becoming commonplace for entry-level certified athletic trainers.

Data Sources:

Various textbooks written on this topic.

Data Synthesis:

The authors collected information from commonly used textbooks on joint mobilization in both athletic training and physical therapy curriculums.

Conclusion:

Undoubtedly, before using joint mobilization, the clinician should demonstrate mastery-level understanding of joint biomechanics, application principles, and indications and contra-indications. This article provides basic information on the principles of joint mobilization.

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Brent C. Mangus, Mark A. Hoffman and Scott A. Parry

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Sam T. Johnson, Grace M. Golden, John A. Mercer, Brent C. Mangus and Mark A. Hoffman

Context:

Form skipping has been used to help injured athletes progress to running. Because little research has been done on form-skipping mechanics, its justification as a progression to running exercises is unclear.

Objective:

To compare ground-reaction forces (GRF) during form skipping and running in healthy subjects at clinically relevant speeds, 1.75 m/s and 3.83 m/s, respectively.

Design:

Dependent t tests (α = .05).

Setting:

Sports-injury research center.

Participants:

9 male college athletes (age 20 ± 1.33 years, mass 848.4 ± 43.24 N, height 1.80 ± 0.07 m).

Main Outcome Measures:

Average (Fz avg) and maximum (Fz max) vertical GRF and (Fy) braking impulse were compared.

Results:

Fz avg and Fz max were greater during running than during form skipping (P < .05). Braking impulses were not different (P > .05).

Conclusions:

It appears that Fz, but not the Fy, GRF might explain why form skipping might be an appropriate progression to running.

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Bradley T. Hayes, Rod A. Harter, Jeffrey J. Widrick, Daniel P. Williams, Mark A. Hoffman and Charlie A. Hicks-Little

Context:

Static stretching is commonly used during the treatment and rehabilitation of orthopedic injuries to increase joint range of motion (ROM) and muscle flexibility. Understanding the physiological adaptations that occur in the neuromuscular system as a result of long-term stretching may provide insight into the mechanisms responsible for changes in flexibility.

Objective:

To examine possible neurological origins and adaptations in the Ia-reflex pathway that allow for increases in flexibility in ankle ROM, by evaluating the reduction in the synaptic transmission of Ia afferents to the motoneuron pool.

Design:

Repeated-measures, case-controlled study.

Setting:

Sports medicine research laboratory.

Participants:

40 healthy volunteers with no history of cognitive impairment, neurological impairment, or lower extremity surgery or injury within the previous 12 mo.

Intervention:

Presynaptic and postsynaptic mechanisms were evaluated with a chronic stretching protocol. Twenty subjects stretched 5 times a wk for 6 wk. All subjects were measured at baseline, 3 wk, and 6 wk.

Main Outcome Measures:

Ankle-dorsiflexion ROM, Hmax:Mmax, presynaptic inhibition, and disynaptic reciprocal inhibition.

Results:

Only ROM had a significant interaction between group and time, whereas the other dependent variables did not show significant differences. The experimental group had significantly improved ROM from baseline to 3 wk (mean 6.2 ± 0.9, P < .001), 3 wk to 6 wk (mean 5.0 ± 0.8, P < .001), and baseline to 6 wk (mean 11.2 ±0.9, P < .001).

Conclusions:

Ankle dorsiflexion increased by 42.25% after 6 wk of static stretching, but no significant neurological changes resulted at any point of the study, contrasting current literature. Significant neuromuscular origins of adaptation do not exist in the Ia-reflex-pathway components after a long-term stretching program as currently understood. Thus, any increases in flexibility are the result of other factors, potentially mechanical changes or stretch tolerance.