In a recent letter,[7] Noakes reminded us that the brain estimates
the maximal exercise duration that can be sustained (maybe even before the
exercise begins), and then uses the ratings of perceived exertion (RPE) to
inform the body when the exercise will and must terminate. I agree with
this suggestion. RPE attests to the exercise intensity, but also to the
duration.[3] Therefore, according to Noake...
In a recent letter,[7] Noakes reminded us that the brain estimates
the maximal exercise duration that can be sustained (maybe even before the
exercise begins), and then uses the ratings of perceived exertion (RPE) to
inform the body when the exercise will and must terminate. I agree with
this suggestion. RPE attests to the exercise intensity, but also to the
duration.[3] Therefore, according to Noakes,[7, 8] RPE is a predictor of
the exercise duration that remains until exhaustion. However, RPE is not
the only perceptual tool that informs us of the exercise end point, and
perhaps not the most effective.
Drawing from the “teleoanticipation” concept,[9] prior to, or early
in an exercise period, the brain estimates the time limit (i.e., Tlim)
that can safely sustained.[8] Then, this predicted Tlim is associated with
the maximal RPE that can be tolerated. During exercise, the brain provides
RPE, which increases as a function of the percentage of the predicted
Tlim, until the attainment of the corresponding tolerated maximal RPE.[8]
Garcin and Billat confirmed that RPE attests to both exercise
intensity and duration.[3] However, these authors[3] found similar results
for a second scale (Estimated Time Limit scale, ETL). This scale predicts
how long the current exercise level can be maintained (i.e., the
estimation of exhaustion time). Therefore, as suggested by Noakes,[7] if
humans may accurately predict the exercise duration that they are or will
be able to sustain at any exercise intensity, ETL may be considered as the
conscious interpretation of the Tlim predicted by teleoanticipation, and
may be more effective than RPE in predicting the time remaining before
exhaustion.
The reliability of ETL scale is established.[1, 5] Moreover, although
the accuracy of this scale must be improved, no significant difference was
found between the Tlim predicted from this scale and those that were
actually measured.[1, 2, 4] Therefore, ETL scale may be associated with
the RPE scale (or substituted for the RPE scale, if the accuracy
improves), not to precisely measure the Tlim predicted by
teleoanticipation, but to provide an estimation of this latter, as
recently suggested.[6]
There are no competing interests.
References
1. Coquart, J. B. J. and M. Garcin. Validity and reliability of
perceptually-based scales during exhausting runs in trained male runners.
Percept Mot Skills. 2007;104:254-266.
2. Coquart, J. B. J., M. Garcin, S. Robin, and R. Matran. Prediction of
exhaustion time from a perceptually-based scale. In 12th International
Congress of the Association des Chercheurs en Activités Physiques et
Sportives. Leuven, Belgium, p. 68, 2007.
3. Garcin, M. and V. Billat. Perceived exertion scales attest to both
intensity and exercise duration. Percept Mot Skills. 2001;93:661-671.
4. Garcin, M., L. Mille-Hamard, and V. Billat. Influence of aerobic
fitness level on measured and estimated perceived exertion during
exhausting runs. Int J Sports Med. 2004;25:270-277.
5. Garcin, M., M. Wolff, and T. Bejma. Reliability of rating scales of
perceived exertion and heart rate during progressive and maximal constant
load exercises till exhaustion in physical education students. Int J
Sports Med. 2003;24:285-290.
6. Joseph, T., B. Johnson, R. A. Battista, G. Wright, C. Dodge, J.P.
Porcari, J. J. De Koning, and F. Foster. Perception of fatigue during
simulated competition. Med Sci Sports Exerc. 2008;40:381-386.
7. Noakes, T. D. RPE as a predictor of the duration of exercise that
remains until exhaustion. Br J Sports Med Oneline [eLetter] 8 January
2008. http://bjsm.bmj.com/cgi/content/abstract/bjsm.2007.043612v1
8. Noakes, T. D., R. J. Snow, and M. A. Febbraio. Linear relationship
between the perception of effort and the duration of constant load
exercise that remains. J Appl Physiol. 2004;96:1571-1573.
9. Ulmer, H. V. Concept of an extracellular regulation of muscular
metabolic rate during heavy exercise in humans by psychophysiological
feedback. Experientia. 1996;52:416-420.
The injected agent with color Doppler– does it matter in tennis
elbow?
We read with great interest the recent randomised, double-blinded
controlled cross-over trial by Dr. Zeisig and colleagues evaluating
ultrasound and color Doppler guided injections in the proximal forearm in
tennis elbow. We would like to comment on some issues.
Grip strength was considered as “the best objective...
The injected agent with color Doppler– does it matter in tennis
elbow?
We read with great interest the recent randomised, double-blinded
controlled cross-over trial by Dr. Zeisig and colleagues evaluating
ultrasound and color Doppler guided injections in the proximal forearm in
tennis elbow. We would like to comment on some issues.
Grip strength was considered as “the best objective outcome measure”
for tennis elbow by the authors. The maximum voluntary grip strength was
evaluated with the elbow straight and the wrist in a neutral position.
Interestingly, elbow position does play a role for grip strength in tennis
elbow [1]. An 8% difference in grip strength between flexion and extension
was found to be 83% accurate in distinguishing the affected from the
unaffected extremities. In other words, grip strength is used to
distinguish tennis elbow from a pain-free extremity based on flexed and
extended elbow position. ECRB’s unique anatomy with a sarcomere length
maximal with the elbow at 90° of flexion, and minimal between 30° of
flexion and 60° of flexion is considered to play a role in this regard. It
would be interesting to see whether the grip strength with 90° elbow
flexion might change as well in response to the injection therapy by
either polidocanol or lidocaine/adrenaline or any other agent.
This idea leads us to another suggestion. Colour Doppler sonography
was performed with the arm resting on a table in 70°-80° elbow flexion and
pronated wrist. On the other hand, as mentioned before, grip strength was
tested on the elbow extended. The area of neovascularisation inside the
area of structural changes in the extensor origin might be influenced by
elbow position as well. One is tempted to speculate that blood flow in the
area of neovascularisation might be changed by elbow extension. In
Achilles tendinopathy, the eccentric position of the ankle has been
reported to reduce the area of neovascularisation [3]. Therefore, it might
be worth considering elbow position for colour Doppler ultrasound as well,
since even in the pilot paper on neovascularisation in tennis elbow [5]
there is no mention why a 70° to 80° position was used and how
neovascularisation might be influenced as a function of elbow flexion.
The authors speculated that regardless of the type of substance
injected, the volume injected might have increased the intratendinous
pressure which might be responsible for the pain relieving effects. Dr.
Zeisig injected 0.5ml per injection with either polidocanol or
lidocaine/adrenaline. A recently published, case-only, blinded
intervention study among 62 patients with tennis elbow performed a colour
Doppler guided injection (90° elbow flexion) of 1ml methylprednisone
(40mg/ml) and 0.5ml lidocaine (1%) [4]. Within two weeks symptoms resolved
which corresponded to a reduction of the vascular activity in the common
extensor origin following the injection. In Achilles tendinopathy, color
Doppler guided injection of 1ml lidocaine (2%) and 1ml of 50% dextrose
yielded to to good clinical responses as far as pain at rest and during
tendon-loading activities was concerned [2].
Studies with various volumes injected by guided color Doppler
ultrasound with clinical outcome scores as well as functional data such as
tendon metabolism or tendon microcirculation might help in the future to
determine the appropiate amount and type of injected agent in tennis
elbow. We would like to thank the authors for their inspiring and
stimulating work.
References
[1] Dorf ER, Chhabra AB, Golish SR, McGinty JL, Pannunzio ME. Effect
of elbow position on grip strength in the evaluation of lateral
epicondylitis. J Hand Surg 2007;32:882-6.
[2] Maxwell NJ, Ryan MB, Taunton JE, Gillies JH, Wong AD.
Sonographically guided intratendinous injection of hyperosmolar dextrose
to treat chronic tendinosis of the Achilles tendon: a pilot study. AJR Am
J Roentgenol 2007;189:W215-20.
[3] Ohberg L, Alfredson H. Effects on neovascularisation behind the
good results with eccentric training in chronic mid-portion Achilles
tendinosis? Knee Surg Sports Traumatol Arthrosc 2004;12:465-70.
[4] Torp-Pedersen TE, Torp-Pedersen ST, Ovistgaard E, Bliddal H.
Effect of glucocorticosteroid injections in tennis elbow verified on
colour doppler ultrasound: evidence of inflammation. Br J Sports Med 2008
Mar 4 [Epub ahead of print].
[5] Zeisig E, Ohberg L, Alfredson H. Extensor origin vascularity
related to pain in patients with tennis elbow. Knee Surg Sports Traumatol
Arthrosc 2006;14:659-63.
Hegedus et al [1] used a fixed-effects model to pool diagnostic odds
ratios (DOR) for the Neer and the Hawkins-Kennedy tests for impingement.
In Figure 2 and in Figure 3 they display the natural logarithms of the DOR
for the individual and pooled results (the figures are inadvertently
labeled as DOR rather than as the logarithms). In each diagram, the null
value (natural logarithm of the DOR =0) is incl...
Hegedus et al [1] used a fixed-effects model to pool diagnostic odds
ratios (DOR) for the Neer and the Hawkins-Kennedy tests for impingement.
In Figure 2 and in Figure 3 they display the natural logarithms of the DOR
for the individual and pooled results (the figures are inadvertently
labeled as DOR rather than as the logarithms). In each diagram, the null
value (natural logarithm of the DOR =0) is included in the confidence
intervals of the pooled results, while it is not included in the
confidence intervals of any of the individual studies. The authors report
that the 95% confidence interval for the pooled DOR crosses 1
(corresponding to a log-odds of 0) indicating that neither test has
diagnostic utility for impingement.
In a fixed-effects model, a weighted average is taken of the odds
ratios of the individual studies. Different calculation methods may arrive
at slightly different confidence intervals for the pooled odds ratio, but
the standard error of the weighted sum is smaller than the standard errors
of the individual studies. It often happens that the confidence intervals
for individual studies may include the value for the null hypothesis,
while the pooled estimate confidence interval excludes that value; this is
one reason that meta-analyses are undertaken. If the converse occurs, a
computational mishap is likely to have occurred. Pooling several
statistically significant odds ratios will not yield a non-significant
odds ratio. In the present meta-analysis, extracting the data from the
four studies and pooling the results may yield a DOR of insufficient
magnitude to discriminate between cases and non-cases of impingement, but
the calculation yielding a DOR whose confidence interval includes 1 should
be re-examined.
References
1. Hegedus EJ et al. Physical examination tests of the shoulder: a
systematic review with meta-analysis of individual tests. Br J Sports Med
2008;42:80-91.
Dear Editor,
In a recent letter,[7] Noakes reminded us that the brain estimates the maximal exercise duration that can be sustained (maybe even before the exercise begins), and then uses the ratings of perceived exertion (RPE) to inform the body when the exercise will and must terminate. I agree with this suggestion. RPE attests to the exercise intensity, but also to the duration.[3] Therefore, according to Noake...
Dear Editor
The injected agent with color Doppler– does it matter in tennis elbow?
We read with great interest the recent randomised, double-blinded controlled cross-over trial by Dr. Zeisig and colleagues evaluating ultrasound and color Doppler guided injections in the proximal forearm in tennis elbow. We would like to comment on some issues.
Grip strength was considered as “the best objective...
Dear Editor
Hegedus et al [1] used a fixed-effects model to pool diagnostic odds ratios (DOR) for the Neer and the Hawkins-Kennedy tests for impingement. In Figure 2 and in Figure 3 they display the natural logarithms of the DOR for the individual and pooled results (the figures are inadvertently labeled as DOR rather than as the logarithms). In each diagram, the null value (natural logarithm of the DOR =0) is incl...
Pages