Cardiovascular Training in Spinal Cord Injury

Original Editor - Naomi O'Reilly

Top Contributors - Naomi O'Reilly, Ewa Jaraczewska, Admin, Tarina van der Stockt, Kim Jackson, Lucinda hampton, Jess Bell, Anas Mohamed, Stacy Schiurring and Olajumoke Ogunleye  

Introduction

Aerobic activity involves the use of oxygen to meet the energy demands of the body’s muscles during exercise. It is associated with longer duration exercise during a given session of training, often at a consistent pace. Regular aerobic training will improve cardiovascular function. With improved cardiovascular function, individuals are more likely to be able to live independently, decrease secondary health complications, and improve muscular endurance.

Definition

According to the Oxford Dictionary of Sport Science and Medicine cardiovascular fitness is the "ability of the heart and blood vessels to supply nutrients and oxygen to tissues, including muscles, during sustained exercise".

Assessment of Cardiovascular Fitness

In order to develop appropriate exercise programs and monitor the response to training it is important to first assess cardiovascular fitness under reproducible test situations, ensuring factors such as the type of ergometer, constraints used, position of individual are standardized. Precautions should also be followed when conducting cardiovascular assessments as strenuous exercise can lead to a cardiovascular event.

Peak Oxygen Consumption Tests

The Peak Oxygen Consumption (VO_{2 Peak}) test, equivalent to the VO_{2 Max} test in able bodied individuals, measures the maximal capacity of the body to deliver oxygen from the lungs to the mitochondria of exercising muscles by expired gas collection, and is the most accurate way to assess cardiovascular fitness in spinal cord injury. The terminology is used to reflect the lower maximal rate of oxygen consumption with arm exercises v leg exercises due to both lower demand for oxygen from smaller muscle groups anand the circulatory implication of arm exercise.

In individuals with a spinal cord injury, the VO_{2 Peak} Test is typically performed using an arm cycle ergometer, but can also be completed with manual wheelchair propulsion or handcycle on an ergometer or treadmill with gradually increasing exercise intensities until exhaustion. Rest periods of 20 - 30 seconds are at times provided for between each increment. Starting points for arm ergometry vary depending on level of spinal cord injury and level of fitness. Power output can be adjusted by changing the cranking velocity and / or externally applied resistance. For example;

• Paraplegia; Start at 30 Watts and increase by 10 - 15 Watts every 2 minutes. Maximal power output is likely to be between 50 - 100 Watts.
• Tetraplegia; Start at 5 Watts and increase by 2.5 - 10 Watts every 2 minutes. Maximal power output is likely to be between 10 - 50 Watts.

While the VO_{2 Peak} is the gold standard method for assessing exercise reponse for an individual with a spinal cord injury, it is rarely used in spinal cord injury units due to the complex nature of the test.

Submaximal Exercise Tests

Submaximal exercise tests are more commonly used in individuals with a spinal cord injury to evaluate the adaptation of the oxygen transport system to exercise below maximal intensity, so that main energy system used is aerobic. While portable expired gases analysis systems can be utilised and are often used in high performance paralympic sport, heart rate measurement is more commonly used in spinal injury rehabilitation units. Use of heart rate measurements does not allow estiamtion of VO_{2 Peak}, but is used as a means to monitor the response of individuals with a spinal cord injury to training, with improvements in cardiovascuar fitness indicated by decreased heart rate at at the same power output with training or improvements in individials perception of exertion with the Borg Exertion Scale.

Performed in a similar way to the VO_{2 Peak} test with a different set of protocols and terminated prior to exhaustion. A wide range of protocols are available to use, and as with VO_{2 Peak} tests, the protocol selected will depend on level of injury, level of fitness, time since injury etc. A commonly use protocl uses 3 x 7 Minute Exercise Bouts of exercise at 40%, 60% and 80% of predicted maximal exercise capacity.

• Paraplegia with High Level of Fitness; 7 mins each at 40 Watts, 60 Watts and 80 Watts
• Tetraplegia; 7 mins each at 20 Watts, 30 Watts and 40 Watts

Submaximal exercise testing appears to have greater applicability to physiotherapists in their role as clinical exercise specialists compared with maximal exercise testing, and much easier to imlement within a spinal injury unit and rehabilitation setting.

Field Exercise Tests

Response to Cardiovascular Fitness Training

Cardiac Output

Heart Rate

Stroke Volume

Aterio-venous Oxygen Difference

Size Exercising Muscle Mass

Ability Muscle to Extract Oxygen

Exercise Prescription

Type

Examples of Cardiovascular Exercise include; Arm Crank Ergometers Cycling Nordic Ski Erg Swimming Wheelchair Pushing Walking

Intensity

Guidelines

Resources

References

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