Special Medical Reports - January 15, 1999 - American Academy of Family Physicians

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Special Medical Reports

ACSM Revises Guidelines for Exercise to Maintain Fitness

SHARON SCOTT MOREY

The American College of Sports Medicine (ACSM) has updated its position stand on the quantity and quality of exercise to maintain cardiorespiratory and muscular fitness. The revised ACSM guidelines include for the first time a recommendation for flexibility training as a component in maintaining fitness in addition to aerobic and strength training exercises.

The ACSM position stand is published in the June 1998 issue of Medicine & Science in Sports & Exercise (vol. 30, no. 6). The 17-page position stand also provides the rationale and supportive research for the recommendations. The following information highlights the ACSM recommendations for exercise in healthy adults.

Cardiorespiratory Fitness and Weight Control

To maintain cardiorespiratory fitness and weight control, the recommendations state that aerobic exercise should be performed three to five days a week for 20 to 60 minutes at an intensity that achieves 55 to 90 percent of the maximum heart rate and 40 to 85 percent of the maximum oxygen uptake reserve. In place of one 20- to 60-minute session on a given day, the recommendations state that two to six 10-minute periods of aerobic activity throughout the day can be used to fulfill the requirements for the amount of exercise.

Lower-intensity exercise is recommended for persons who are unfit. Lower-intensity exercise should be performed for 30 minutes or more. Persons training at higher levels should exercise for at least 20 minutes. Moderate-intensity exercise for a longer duration is recommended for most adults.

Muscular Strength

According to the recommendations, resistance training should be a part of a fitness program and of sufficient intensity to enhance muscular strength and endurance and to maintain a fat-free mass. One set of eight to 10 exercises that work the major muscle groups should be performed two or three days a week. The guidelines advocate for most persons eight to 12 repetitions (or to a near-fatigue level) of each exercise. Persons who are older or frail may benefit from 10 to 15 repetitions.

The recommendations for resistance training are based on three factors: a practical amount of time to perform resistance training, the degree of training that results in improved muscular strength and endurance, and the suitability of the level of resistance training for most adults. With respect to the amount of time, the position stand notes that higher dropout rates occur when more than 60 minutes is required to complete a session. A previous study revealed that only 20 minutes is required to complete one set of weight-training exercises, whereas 50 minutes is required to complete three sets. While more frequent training and additional sets and repetitions may produce larger gains in strength, the difference in improvement is usually small in the average healthy adult, plus the average adult does not have the same goals as an athlete. In addition, more intense resistance training may increase the risk of orthopedic injury or a cardiac event in middle-aged and older participants.

Flexibility Training

The recommendations state that flexibility exercises two or three days a week should be incorporated into the fitness program. At least four repetitions per muscle group should be completed at each session. Stretching exercises should mobilize the major muscle and tendon groups and may include static, proprioceptive neuromuscular facilitation and ballistic techniques.

With the static technique, the tendons and muscles are slowly stretched and the stretched position is held for a period of time. Static stretches should be held for 10 to 30 seconds. Proprioceptive neuromuscular facilitation stretching consists of alternating isometric muscle contraction and passive stretching. This technique is sometimes described as active/assisted, contract/relax or hold/relax. Proprioceptive neuromuscular facilitation stretching should be maintained for a six-second contraction, followed by a 10- to 30-second assisted stretch. Ballistic stretching involves repetitive bouncing motions in which the tendon is rapidly stretched and relaxed.

ACOG Urges a Cautious Approach to Vaginal Birth After Cesarean Delivery

VERNA ROSE

While strongly supporting the concept of vaginal birth after previous cesarean (VBAC) delivery, the American College of Obstetricians and Gynecologists (ACOG) has issued an updated practice pattern that recommends a more cautious approach and consideration of individual risk factors before attempting a trial of labor. The report discusses the background of VBAC, clinical considerations and recommendations, selection of candidates for a trial of labor, risks and benefits, contraindications for VBAC, management of labor in patients undergoing VBAC and counseling patients. An algorithm for determining the feasibility of VBAC in a patient is also included in the ACOG report. ACOG Practice Pattern No. 2 was published in the October 1998 issue of Obstetrics and Gynecology.

According to ACOG, improvements in obstetric care over the years have made a trial of labor relatively safe for both mother and infant. However, VBAC has been associated with a risk of uterine rupture, and other maternal and infant complications have been associated with an unsuccessful trial of labor. The occurrence of uterine rupture appears to be associated with the type and location of the previous incision. ACOG states that of the four types of incisions for cesarean delivery (classical, T-incision, low vertical and low transverse), low-transverse scars are least likely to rupture.

ACOG emphasizes that it is ultimately up to the physician and patient to decide whether to attempt VBAC, and ACOG strongly objects to any mandate by a third party for a trial of labor after previous cesarean delivery. The following are the criteria that ACOG lists for selecting a candidate for VBAC:

One or two prior low-transverse cesarean deliveries.

Clinically adequate pelvis.

No other uterine scars or previous rupture.

Physician readily available throughout labor capable of monitoring labor and performing an emergency cesarean delivery.

Availability of anesthesia and personnel for emergency cesarean delivery.

VBAC should not be undertaken in women who have had a prior classic or T-shaped incision or who have had other transfundal uterine surgery. Other contraindications for VBAC are a contracted pelvis, medical or obstetric complication that precludes vaginal delivery, and an inability to perform immediate emergency cesarean delivery. ACOG also notes that a combination of factors, which by themselves may not be compelling for cesarean delivery, may influence a decision to forego VBAC.

The following recommendations from ACOG, based on consistent scientific evidence, have been excerpted from the practice pattern:

Most women with one previous cesarean delivery with a low-transverse incision are candidates for VBAC and should be counseled about VBAC and offered a trial of labor.

Epidural anesthesia may be used for VBAC.

A previous uterine incision extending into the fundus is a contraindication.

These following recommendations are, according to ACOG, based on limited or inconsistent scientific evidence:

Women with two previous low-transverse cesarean deliveries and no contraindications who wish to attempt VBAC may be allowed a trial of labor. They should be advised that the risk of uterine rupture increases as the number of cesarean deliveries increases.

Use of oxytocin or prostaglandin gel for VBAC requires close patient monitoring.

Women with a vertical incision within the lower uterine segment that does not extend into the fundus are candidates for VBAC.

These following recommendations are based on consensus and expert opinion:

VBAC should only be attempted in institutions equipped to respond to emergencies with physicians readily available to provide emergency care.

After thorough counseling that weighs the individual benefits and risks of VBAC, the ultimate decision to attempt this procudure or undergo a repeat cesarean delivery should be made by the patient and her physician.

To order copies of the practice pattern or obtain further information, call ACOG at 800-762-2264, ext. 784.

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