HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Free Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content

POINT-COUNTERPOINT

Rebuttal from Drs. Green, Maiorana, and Cable

We respond:

1. ) They mention a number papers that have failed to demonstrate upper limb vascular adaptation to lower limb training. Twenty-two of the 30 papers that have studied upper limb function after lower limb exercise have demonstrated adaptations (Table 1). Some of those quoted as contrary actually showed similar upper and lower limb changes (2) and, as our antagonists suggest, others may not have achieved a systemic hemodynamic/shear stimulus sufficient to induce global adaptation (8).
   
2. ) After acknowledging shear stress as a stimulus to vascular adaptation, they state that BF only minimally increases in the nonactive upper limbs during leg exercise. Even if mean flows do not substantially increase, large changes in the pattern of flow can occur (3, 7). The flow/shear pattern presents to the artery wall as a stimulus.
   
3. ) They propose that leg exercise involves "moderate" arm activity that explains the vascular adaptation. We cannot speak for other studies, but we demonstrated forearm arterial adaptation despite upper limb exercise being largely avoided (5, 6, 9, 10). Also, cycling causes substantial upper limb shear pattern changes that induce NO release when the forearms are passively supported (3, 7).
   
4. ) Functional electric stimulation (FES) in spinal cord injury (SCI) is proposed as a model in which the common femoral artery (CFA) experiences a shear stress/hemodynamic stimulus sufficient to induce vascular adaptation, yet the superficial femoral artery (SFA), 5 cm downstream, does not (8). In this paper (p. 1116), an explanation is given that "Apparently, the stimulus [shear] is not sufficient to induce vascular adaptation [in the SFA]..." This is an implicit acknowledgment of our argument, i. e., where large muscle group exercise does cause a shear/pressure stimulus of sufficient magnitude, such a stimulus can induce vascular adaptations in itself, without localized muscle activity. In another study of SCI subjects, who represent a model of upper limb exercise training, preserved/enhanced FMD was observed in the SFA (1)!
   

Arguments are to be avoided: they are always vulgar and often convincing

We agree that there is little extant evidence that training induces structural adaptations beyond the active muscle beds. We also agree that the nature of the exercise stimulus might determine whether shear/pressure signals are sufficient to induce functional adaptation in nonactive beds. Different types of exercise certainly induce different shear/hemodynamic patterns (3). We propose the adoption of direct vascular flow/shear measurements during exercise to quantify the stimulus to vascular adaptations (4).

REFERENCES

1. De Groot PC, Poelkens F, Kooijman M, Hopman MT. Preserved flow-mediated dilation in the inactive legs of spinal cord-injured individuals. Am J Physiol Heart Circ Physiol 287: H374–H380, 2004.[Abstract/Free Full Text]
2. Gocke N, Vita JA, Bader DS, Sherman DL, Hunter LM, Holbrook M, O'Malley C, Keaney JF, Balady GJ. Effect of exercise on upper and lower extremity endothelial function in patients with coronary artery disease. Am J Cardiol 90: 124–127, 2002.[CrossRef][Web of Science][Medline]
3. Green DJ, Bilsborough W, Naylor LH, Reed C, Wright J, O'Driscoll G, Walsh JH. Comparison of forearm blood flow responses to incremental handgrip and cycle ergometer exercise: relative contribution of nitric oxide. J Physiol 562: 617–628, 2005.[Abstract/Free Full Text]
4. Green DJ, Cable NT, Joyner MJ, O'Driscoll G. Viewpoint: Exercise and cardiovascular risk reduction: updating the rationale for exercise. J Appl Physiol; doi:10.1152/japplphysiol.01028.2007.[Free Full Text]
5. Maiorana A, O'Driscoll G, Cheetham C, Dembo L, Stanton K, Goodman C, Taylor RR, Green DJ. The effect of combined aerobic and resistance exercise training on vascular function in type 2 diabetes. J Am Coll Cardiol 38: 860–866, 2001.[Abstract/Free Full Text]
6. Maiorana A, O'Driscoll G, Dembo L, Cheetham C, Goodman C, Taylor R, Green DJ. Effect of aerobic and resistance exercise training on vascular function in heart failure. Am J Physiol Heart Circ Physiol 279: H1999–H2005, 2000.[Abstract/Free Full Text]
7. Tanaka H, Shimizu S, Ohmori F, Muraoka Y, Kumagai M, Yoshizawa M, Kagaya A. Increases in blood flow and shear stress to nonworking limbs during incremental exercise. Med Sci Sports Exerc 38: 81–85, 2006.[CrossRef][Web of Science][Medline]
8. Thijssen DH, Heesterbeek P, van Kuppevelt DJ, Duysens J, Hopman MT. Local vascular adaptations after hybrid training in spinal cord-injured subjects. Med Sci Sports Exerc 37: 1112–1118, 2005.[CrossRef][Web of Science][Medline]
9. Walsh JH, Best M, Maiorana AJ, Taylor RR, O'Driscoll GJ, Green DJ. Exercise improves conduit vessel endothelial function in CAD patients. J Appl Physiol 285: 20–25, 2003.
10. Walsh JH, Yong G, Cheetham C, Watts GF, O'Driscoll GJ, Taylor RR, Green DJ. Effect of exercise training on conduit and resistance vessel function in medicated and unmedicated hypercholesterolaemic patients. Eur Heart J 24: 1681–1689, 2003.[Abstract/Free Full Text]

This Article Full Text (PDF) Free Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content