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Clinical Education: We Aren’t There Yet, but We’re Making Progress!
Kenneth L. Knight
Reliability and Validity of Electrothermometers and Associated Thermocouples
Lisa S. Jutte, Kenneth L. Knight, and Blaine C. Long
Objective:
Examine thermocouple model uncertainty (reliability + validity).
Design:
First, a 3 × 3 repeated measures design with independent variables electrothermometers and thermocouple model. Second, a 1 × 3 repeated measures design with independent variable subprobe.
Intervention:
Three electrothermometers, 3 thermocouple models, a multi-sensor probe and a mercury thermometer measured a stable water bath.
Main Outcome Measures:
Temperature and absolute temperature differences between thermocouples and a mercury thermometer.
Results:
Thermocouple uncertainty was greater than manufactures’ claims. For all thermocouple models, validity and reliability were better in the Iso-Themex than the Datalogger, but there were no practical differences between models within an electrothermometers. Validity of multi-sensor probes and thermocouples within a probe were not different but were greater than manufacturers’ claims. Reliability of multiprobes and thermocouples within a probe were within manufacturers claims.
Conclusion:
Thermocouple models vary in reliability and validity. Scientists should test and report the uncertainty of their equipment rather than depending on manufactures’ claims.
Isotonic Contractions Might Be More Effective than Isokinetic Contractions in Developing Muscle Strength
Kenneth L Knight, Christopher D Ingersoll, and John Bartholomew
Problem:
Isokinetic contractions are thought to be superior to isotonic contractions for developing strength because resistance during them is greater. Because isokinetic resistance is accommodating, however, it decreases with fatigue. It is constant during multiple repetitions, so an aggressive isotonic procedure should produce more force as the muscle fatigues, which would be an advantage in strength development.
Purpose:
To compare force production in isokinetic and isotonic muscle contractions at the beginning and end of a set of fatiguing repetitions.
Methods:
Subjects performed 25 maximal-effort isokinetic knee extensions at 60°/s. After 25–72 hours, they performed maximal repetitions isotonically using 70% of the isokinetic peak torque with speed set at a maximum of 300°/s.
Results:
Peak force during the first 3 repetitions was greater isokinetically, but average force was similar. During the last 3 repetitions, isotonic force was higher than isokinetic force.
Conclusion:
Muscle is more active as it nears fatigue during an isotonic contraction. These data support the hypothesis that isotonic contractions recruit extra motor units at the point of fatigue.
