Effects of Acute Leg Ischemia during Cycling on Oxygen and Carbon Dioxide Stores

By Loeppky, Jack A.; Gurney, Burke et al. | Journal of Rehabilitation Research & Development, September 2008 | Go to article overview

Effects of Acute Leg Ischemia during Cycling on Oxygen and Carbon Dioxide Stores


Loeppky, Jack A., Gurney, Burke, Icenogle, Milton V., Journal of Rehabilitation Research & Development


INTRODUCTION

Progressive physical deconditioning is common in patients with chronic diseases, such as congestive heart failure and chronic obstructive pulmonary disease. One limitation these patients face is an inability to exercise with sufficient intensity to provide adequate training stimuli. However, regional training of muscles without taxing the central circulation can improve whole-body exercise capacity in these patients [1]. An unusual potential tool to facilitate regional muscle rehabilitation is exercise training during reduced limb blood flow [2-3]. Such "ischemic limb training" with limb pressure cuffs has improved limb strength and exercise endurance in physically fit subjects [4-5], diminished postoperative disuse atrophy of knee extensors [6], and induced favorable biochemical and structural changes in muscles [7-8]. Ischemic limb training with low-intensity exercise in patients with congestive heart failure has also reduced exertional dyspnea [9]. We recently demonstrated that leg-extension exercise endurance was enhanced with a 6-week training program of very light leg-extension exercise with ischemia induced by thigh cuff inflation [10].

Superimposing ischemia on exercising limbs provokes the muscle metaboreflex, whereby pulmonary ventilation ([[??].sub.E]) and systemic blood pressure are elevated by a chemoreflex stimulated by buildup of metabolic byproducts in the ischemic limbs; the most likely candidate is hydrogen ion concentration ([H.sup.+]) [11]. The oxygen ([O.sub.2]) stores ([O.sub.2]s) and carbon dioxide ([CO.sub.2]) stores ([CO.sub.2]s) in the region where blood flow is occluded, as well as in the whole body, will be affected during this ischemia and after circulation is restored as a result of ventilatory, blood flow, and biochemical perturbations. The magnitude and time course of these gas store changes will affect regional and whole-body acid-base status, will cause secondary ventilatory and gas exchange fluctuations during and after exercise, and may induce transient hypoxemia and hypercapnia, such as noted following passive changes in posture [12].

Although rapid transient changes in [O.sub.2]s and [CO.sub.2]s during exercise workload transitions have been studied and quantified [13], gas store changes induced by limb ischemia have received little attention. Specifically, the quantitative relationship is not well defined between [O.sub.2] repayment and [CO.sub.2] elimination after exercise requiring energy partially derived from anaerobic sources [14] and these measurements with the anaerobic component artificially superimposed have not been reported. Therefore, this study was an initial attempt to estimate the time course and magnitude of changes in [O.sub.2]s and [CO.sub.2]s during and after acute, temporary ischemia of the legs applied by cuff inflation during steady state exercise on a cycle ergometer.

METHODS

Subjects

Five men and one woman volunteered as subjects. Informed consent was obtained from each person, as approved by the University of New Mexico Human Research Review Committee. All were physically fit and regularly taking part in physical recreation and fitness activities, including jogging and cycling. Their ages ranged from 24 to 62 yr, with a mean body weight and body mass index of 82.5 kg and 25.0 kg/[m.sup.2], respectively. Their maximal [O.sub.2] uptake ([??][O.sub.2]max) averaged 48 [mL.min.sup.-1].[kg.sup.-1] (range: 42-56). The [O.sub.2] uptake ([??][O.sub.2]) during exercise before ischemia (baseline) averaged 35.7 percent (range: 30%-42%, standard error of the mean = 1.7%) of the subjects' [??][0.sub.2max]. This percentage was not related to age (r = -0.22).

Ergometer Exercise and Inflation Cuffs

We placed cuffs on each upper thigh (SC-17, Hokanson Co; Bellevue, Washington) and each lower leg (SC22) using adhesive tape to keep them in position during exercise. …

The rest of this article is only available to active members of Questia

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Note: primary sources have slightly different requirements for citation. Please see these guidelines for more information.

Cited article

Effects of Acute Leg Ischemia during Cycling on Oxygen and Carbon Dioxide Stores
Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Help
Full screen
Items saved from this article
  • Highlights & Notes
  • Citations
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

matching results for page

    Questia reader help

    How to highlight and cite specific passages

    1. Click or tap the first word you want to select.
    2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
    3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

    OK, got it!

    Cited passage

    Style
    Citations are available only to our active members.
    Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

    1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

    Cited passage

    Thanks for trying Questia!

    Please continue trying out our research tools, but please note, full functionality is available only to our active members.

    Your work will be lost once you leave this Web page.

    Buy instant access to save your work.

    Already a member? Log in now.

    Search by... Author
    Show... All Results Primary Sources Peer-reviewed

    Oops!

    An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.