Isometric torso rotation strength: effect of training frequency on its development

Measurement of Axial Rigidity and Postural Instability Using Wearable Sensors

Axial Bradykinesia is an important feature of advanced Parkinson's disease (PD). The purpose of this study is to quantify axial bradykinesia using wearable sensors with the long-term aim of quantifying these movements, while the subject performs routine domestic activities. We measured back movements during common daily activities such as pouring, pointing, walking straight and walking around a chair with a test system engaging a minimal number of Inertial Measurement (IM) based wearable sensors. Participants included controls and PD patients whose rotation and flexion of the back was captured by the time delay between motion signals from sensors attached to the upper and lower back. PD subjects could be distinguished from controls using only two sensors. These findings suggest that a small number of sensors and similar analyses could distinguish between variations in bradykinesia in subjects with measurements performed outside of the laboratory. The subjects could engage in routine activities leading to progressive assessments of therapeutic outcomes.

Electromyographic studies in abdominal exercises: a literature synthesis

OBJECTIVE

The purpose of this article is to synthesize the literature on studies that investigate electromyographic activity of abdominal muscles during abdominal exercises performance.

METHODS

MEDLINE and Sportdiscus databases were searched, as well as the Web pages of electronic journals access, ScienceDirect, and Swetswise, from 1950 to 2008. The terms used to search the literature were abdominal muscle and the specific names for the abdominal muscles and their combination with electromyography, and/or strengthening, and/or exercise, and/or spine stability, and/or low back pain. The related topics included the influence of the different exercises, modification of exercise positions, involvement of different joints, the position with supported or unsupported segments, plane variation to modify loads, and the use of equipment. Studies related to abdominal conditioning exercises and core stabilization were also reviewed.

RESULTS

Eighty-seven studies were identified as relevant for this literature synthesis. Overall, the studies retrieved lacked consistency, which made it impossible to extract aggregate estimates and did not allow for a rigorous meta-analysis. The most important factors for the selection of abdominal strengthening exercises are (a) spine flexion and rotation without hip flexion, (b) arm support, (c) lower body segments involvement controlling the correct performance, (d) inclined planes or additional loads to increase the contraction intensity significantly, and (e) when the goal is to challenge spine stability, exercises such as abdominal bracing or abdominal hollowing are preferable depending on the participants' objectives and characteristics. Pertaining to safety criteria, the most important factors are (a) avoid active hip flexion and fixed feet, (b) do not pull with the hands behind the head, and (c) a position of knees and hips flexion during upper body exercises.

CONCLUSIONS

Further replicable studies are needed to address and clarify the methodological doubts expressed in this article and to provide more consistent and reliable results that might help us build a body of knowledge on this topic. Future electromyographic studies should consider addressing the limitations described in this review.

Prescribing physical activity: applying the ACSM protocols for exercise type, intensity, and duration across 3 training frequencies

When physicians advise patients to attain more physical activity, they usually recommend a walking program. However, in a similar way to no exercise, those embarking on a walking program will typically lose 4 to 6 lb of lean weight and reduce their resting metabolic rate 2% to 3% every decade. These effects may be mitigated by the inclusion of resistance exercise. The American College of Sports Medicine (ACSM) minimum exercise guidelines recommend 20 minutes of aerobic activity 3 days per week, and 1 set (8-12 repetitions) of 8 to 10 resistance exercises to train the major muscle groups 2 days per week. However, large-scale testing of these recommendations in a field setting has been minimal. Men and women between 21 and 80 years (N = 1725) [corrected] participated in a 10-week combined strength and aerobic activity program based on the ACSM protocols for exercise intensity and duration across 3 training frequencies (1, 2, or 3 sessions/week). Across all training frequencies, mean changes included a reduction in body fat of 1.97%, a decrease in fat weight of 1.7 kg, an increase in lean weight of 1.35 kg, a reduction in systolic blood pressure of 3.83 mm Hg, and a reduction in diastolic blood pressure of 1.73 mm Hg. More frequent weekly training sessions were associated with greater improvements in body fat percent, fat weight, and lean weight. Participants responded favorably to the ACSM exercise program with a 91% completion rate and a 95% satisfaction rating. This article presents recommendations for prescribing safe, effective, and time-efficient exercise programs.

Low-volume muscular endurance and strength training during 3-week forearm immobilization was effective in preventing functional deterioration

Purpose

The purpose of this study was to determine whether endurance and strength hand grip exercises during 3-week upper limb immobilization preserve muscle oxidative capacity, endurance performance and strength.

Methods

Ten healthy adult men underwent non-dominant forearm immobilization by plaster cast for 21 days. Five healthy adult subjects were designated as the immobilization (IMM) group and five were designated as the immobilization + training (IMM+TRN) group. Grip strength, forearm circumference, dynamic handgrip endurance and muscle oxygenation response were measured before and after the 21 day immobilization period. Using near-infrared spectroscopy (NIRS), muscle oxygen consumption recovery (VO₂mus) was recorded after a submaximal exercise and the recovery time constant (TcVO₂mus) was calculated. Reactive hyperemic oxygenation recovery was evaluated after 5 minutes ischemia. Two training programs were performed by the IMM+TRN group twice a week. One exercise involved a handgrip exercise at 30% maximum voluntary contraction (MVC) at a rate of 1 repetition per 1 second until exhaustion (about 60 seconds). The other involved a handgrip exercise at 70% MVC for 2 seconds with a 2 second rest interval, repeated 10 times (40 seconds).

Results

There was a significant group-by-time interaction between the IMM and IMM+TRN groups in the TcVO₂mus (p = 0.032, F = 6.711). A significant group-by-time interaction was observed between the IMM and IMM+TRN groups in the MVC (p = 0.001, F = 30.415) and in grip endurance (p = 0.014, F = 9.791). No significant group-by-time interaction was seen in forearm circumference and reactive hyperemic oxygenation response either in IMM or IMM+TRN group.

Conclusion

The training programs during immobilization period used in this experiment were effective in preventing a decline in muscle oxidative function, endurance and strength.

Trunk rotational strength asymmetry in adolescents with idiopathic scoliosis: an observational study

Background

Recent reports have suggested a rotational strength weakness in rotations to the concave side in patients with idiopathic scoliosis. There have been no studies presenting normative values of female adolescent trunk rotational strength to which a comparison of female adolescents with idiopathic scoliosis could be made. The purpose of this study was to determine trunk rotational strength asymmetry in a group of female adolescents with AIS and a comparison group of healthy female adolescents without scoliosis.

Methods

Twenty-six healthy adolescent females served as the healthy group (HG) (average age 14 years) and fourteen otherwise healthy adolescent females with idiopathic scoliosis served as the idiopathic scoliosis group (ISG) (average age 13.5 years, average Cobb 28°). Participant's isometric trunk rotational strength was measured in five randomly ordered trunk positions: neutral, 18° and 36° of right and left pre-rotation. Rotational strength asymmetry was compared within each group and between the two groups using several different measures.

Results

The HG showed strength asymmetry in the 36° pre-rotated trunk positions when rotating towards the midline (p < 0.05). The ISG showed strength asymmetry when rotating towards the concavity of their primary curve from the neutral position (p < 0.05) and when rotating towards the concavity from the 18° (p < 0.05) and 36° (p < 0.05) concave pre-rotated positions. The ISG is significantly weaker than the HG when rotating away from the midline toward the concave (ISG)-left (HG) side from the concave/left pre-rotated 18° (p < 0.05) and 36° (p < 0.05) positions.

Conclusion

The AIS females were found to be significantly weaker when contracting toward their main curve concavity in the neutral and concave pre-rotated positions compared to contractions toward the convexity. These weaknesses were also demonstrated when compared to the group of healthy female adolescent controls. Possible mechanisms for the strength asymmetry in ISG are discussed.

Reliability of the Assessment of Lumbar Range of Motion and Maximal Isometric Strength

OBJECTIVE

To examine the interobserver reliability and intrasubject variability of the assessment of lumbar range of motion (ROM) and maximal isometric strength in asymptomatic subjects by using commercially available equipment.

DESIGN

A cross-sectional repeated-measures design.

SETTING

Ambulatory care in a university hospital.

PARTICIPANTS

Convenience sample of 61 asymptomatic healthy subjects aged 20 to 55 years.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Six movements of the lumbar spine were assessed with commercially available equipment. Both the ROM and the maximal isometric strength for flexion, extension, lateroflexion, and rotation of the lumbar spine were assessed by 2 investigators who were blinded to the outcome of the assessment performed by their colleague.

RESULTS

The intraclass correlation coefficient (ICC) was above .95 for all the strength measurements. For the assessment of the ROM of the lumbar spine, the ICC varied between .77 and .94. There was a significant intrasubject variability for 8 of 12 measurements.

CONCLUSIONS

The interobserver reliability is excellent for the measurement of the maximal isometric strength and good for the assessment of the ROM of the lumbar spine. There is a significant intrasubject variability, which requires the use of the mean or the best value of different trials.

Movement velocity in resistance training

Guidelines for resistance training include the number of exercises, sets, repetitions, and frequency of training, but only vaguely mention movement velocity. Nevertheless, different velocities imply different performances, i.e. a different number of repetitions or different loads. Studies investigating the effect of different movement velocities on resistance training have not reached a consensus. Some studies indicate specificity in strength gains while others indicate generality. Some indicate slow training to be better, others indicate fast training, and still others indicate no differences. Most of these studies were conducted on isokinetic or hydraulic equipment. Very few used isotonic equipment for training, and their results seem to tend towards generality and no differences in gains of strength between velocities. Defining the training velocity is mostly important for athletic performances where a wide range of velocities is needed and transfer of gains would greatly optimise training. At the other end of the spectrum, there are the most frail and elderly, to whom power loss may impair even daily functions, but training with fast velocities might increase injury risk and, therefore, transfer of gains from slow training would be greatly beneficial. Movement velocity for resistance training with isotonic equipment needs to be further investigated so that recommendations may be made.

Comparison of short- and long-term outcomes for aggressive spine rehabilitation delivered two versus three times per week

BACKGROUND CONTEXT

Rehabilitation services using intensive exercise for the treatment of chronic spinal pain have traditionally been scheduled at a frequency of three times per week.

PURPOSE

In an attempt to reduce the cost of rehabilitation services, this study was designed to determine whether treatment offered two times per week could produce similar outcomes when compared with an established three times per week spine therapy program.

STUDY DESIGN

Prospective cohort study.

PATIENT SAMPLE

Seventy-seven consecutive patients with chronic spinal pain were treated with aggressive spine rehabilitation either two or three times per week.

OUTCOME MEASURES

Flexibility, trunk strength and lifting capacity were quantified before and after treatment. Pain visual analog scores and Oswestry disability scores were measured before and after treatment, as well as 12 months after treatment.

METHODS

A two times per week physical therapy program was developed to be identical in its treatment method to an established three times per week, group-oriented physical therapy program used for the treatment of chronic spinal pain. Patients with spinal pain who continued to work despite chronic pain complaints were allowed to choose between the two therapy programs based on availability of treatment slots and convenience. Treatment consisted of non-pain contingent quota-based exercises targeting identified physical impairments. Treatment sessions lasted for 2 hours and consisted of 30 minutes of stretching, 30 minutes of low-impact step aerobics class and 1 hour of exercise on strength and endurance equipment. Therapy occurred in groups consisting of a maximum of eight patients who were closely supervised by two therapists. Targeted treatment time was 6 weeks. At 12 months after treatment, subjects were surveyed by mailed questionnaires.

RESULTS

Seventy-seven patients with chronic spinal pain with a mean duration of symptoms of 32 months underwent treatment. Twenty-four subjects opted for the twice per week and 53 opted for the three times per week treatment. Seventy-one percent of subjects responded to the 12-month follow-up questionnaire. Physical and self-reported measures improved with both treatment frequencies. There were no differences in outcomes between treatment frequencies for measured flexibility, trunk strength, lifting capacity, pain intensity scores or Oswestry scores at the completion of treatment. At 12-month follow-up, no differences were noted between treatment frequencies for pain scores, Oswestry scores, patients' perceptions of adequacy of treatment, posttreatment exercise compliance or use of other treatments for their spinal problem. Total therapy visits were less in the two than three times per week groups (12 vs 15 visits).

CONCLUSION

Similar outcomes were obtained from aggressive spine rehabilitation occurring two versus three times per week in patients presenting with moderate levels of chronic spinal pain. Reduction in physical therapy services and therefore cost did not adversely affect clinical outcomes in the treatment of this patient population.

Prescription of resistance training for healthy populations

Although there are well documented protective health benefits conferred by regular physical activity, most individuals of all ages are not physically active at a level for sufficient maintenance of health. Consequently, a major public health goal is to improve the collective health and fitness levels of all individuals. The American College of Sports Medicine (ACSM) and other international organisations have established guidelines for comprehensive exercise programmes composed of aerobic, flexibility and resistance-exercise training. Resistance training is the most effective method available for maintaining and increasing lean body mass and improving muscular strength and endurance. Furthermore, there is an increasing amount of evidence suggesting that resistance training may significantly improve many health factors associated with the prevention of chronic diseases. These health benefits can be safely obtained by most segments of the population when prescribed appropriate resistance-exercise programmes. Resistance-training programmes should be tailored to meet the needs and goals of the individual and should incorporate a variety of exercises performed at a sufficient intensity to enhance the development and maintenance of muscular strength and endurance, and lean body mass. A minimum of 1 set of 8 to 10 exercises (multi-joint and single joint) that involve the major muscle groups should be performed 2 to 3 times a week for healthy participants of all ages. More technical and advanced training including periodised multiple set regimens and/or advanced exercises may be more appropriate for individuals whose goals include maximum gains in strength and lean body mass. However, the existing literature supports the guidelines as outlined in this paper for children and adults of all ages seeking the health and fitness benefits associated with resistance training.

Exercise prescription for the elderly: current recommendations

The benefits for elderly individuals of regular participation in both cardiovascular and resistance-training programmes are great. Health benefits include a significant reduction in risk of coronary heart disease, diabetes mellitus and insulin resistance, hypertension and obesity as well as improvements in bone density, muscle mass, arterial compliance and energy metabolism. Additionally, increases in cardiovascular fitness (maximal oxygen consumption and endurance), muscle strength and overall functional capacity are forthcoming allowing elderly individuals to maintain their independence, increase levels of spontaneous physical activity and freely participate in activities associated with daily living. Taken together, these benefits associated with involvement in regular exercise can significantly improve the quality of life in elderly populations. It is noteworthy that the quality and quantity of exercise necessary to elicit important health benefits will differ from that needed to produce significant gains in fitness. This review describes the current recommendations for exercise prescriptions for the elderly for both cardiovascular and strength/resistance-training programmes. However, it must be noted that the benefits described are of little value if elderly individuals do not become involved in regular exercise regimens. Consequently, the major challenges facing healthcare professionals today concern: (i) the implementation of educational programmes designed to inform elderly individuals of the health and functional benefits associated with regular physical activity as well as how safe and effective such programmes can be; and (ii) design interventions that will both increase involvement in regular exercise as well as improve adherence and compliance to such programmes.

Once-weekly resistance exercise improves muscle strength and neuromuscular performance in older adults

OBJECTIVE

To determine the effect of frequency of resistive training on gain in muscle strength and neuromuscular performance in healthy older adults.

DESIGN

A randomized controlled trial with subjects assigned either to high-intensity resistance training 1 (EX1), 2 (EX2), or 3 (EX3) days per week for 24 weeks or to a control group (CO).

SETTING

An exercise facility at an academic medical center.

SUBJECTS

Forty-six community-dwelling healthy men (n = 29) and women (n = 17) aged 65 to 79 years.

INTERVENTION

Progressive resistance training consisting of three sets of eight exercises targeting major muscle groups of the upper and lower body, at 80% of one-repetition maximum (1-RM) for eight repetitions, either 1, 2, or 3 days per week.

MEASURES

Dynamic muscle strength (1-RM) using isotonic equipment every 4 weeks, bone mineral density and body composition by dual energy X-ray absorptiometry (DXA), and neuromuscular performance by timed chair rise and 6-meter backward tandem walk.

RESULTS

For each of the eight exercises, muscle strength increased in the exercise groups relative to CO (P < .01), with no difference among EX1, EX2 and EX3 groups at any measurement interval. Percent change averaged 3.9 +/- 2.4 (CO), 37.0 +/- 15.2 (EX1), 41.9 +/- 18.2 (EX2), and 39.7 +/- 9.8 (EX3). The time to rise successfully from the chair 5 times decreased significantly (P < .01) at 24 weeks, whereas improvement in the 6-meter backward tandem walk approached significance (P = .10) in the three exercise groups compared with CO. Changes in chair rise ability were correlated to percent changes in quadriceps strength (r = -0.40, P < .01) and lean mass (r = -0.40, P < .01).

CONCLUSIONS

A program of once or twice weekly resistance exercise achieves muscle strength gains similar to 3 days per week training in older adults and is associated with improved neuromuscular performance. Such improvement could potentially reduce the risk of falls and fracture in older adults.

Prescription of resistance training for health and disease

When prescribed appropriately, resistance training is effective for developing fitness, health, and for the prevention and rehabilitation of orthopedic injuries. Because resistance training is an integral component in the comprehensive health program promoted by the major health organizations (e.g., American College of Sports Medicine, American Heart Association, American Association of Cardiovascular and Cardiopulmonary Rehabilitation, Surgeon General's Office), population-specific guidelines have recently been published. The current research indicates that, for healthy persons of all ages and many patients with chronic diseases, single set programs of up to 15 repetitions performed a minimum of 2 d x wk(-1) are recommended. Each workout session should consist of 8-10 different exercises that train the major muscle groups. Single set programs are less time consuming and more cost efficient, which generally translates into improved program compliance. Further, single set programs are recommended for the above-mentioned populations because they produce most of the health and fitness benefits of multiple set programs. The goal of this type of program is to develop and maintain a significant amount of muscle mass, endurance, and strength to contribute to overall fitness and health. Patients with chronic diseases (e.g., arthritis) may have to limit range of motion for some exercises and use lighter weights with more repetitions.

American College of Sports Medicine Position Stand. The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness, and flexibility in healthy adults

ACSM Position Stand on The Recommended Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory and Muscular Fitness, and Flexibility in Adults. Med. Sci. Sports Exerc., Vol. 30, No. 6, pp. 975-991, 1998. The combination of frequency, intensity, and duration of chronic exercise has been found to be effective for producing a training effect. The interaction of these factors provide the overload stimulus. In general, the lower the stimulus the lower the training effect, and the greater the stimulus the greater the effect. As a result of specificity of training and the need for maintaining muscular strength and endurance, and flexibility of the major muscle groups, a well-rounded training program including aerobic and resistance training, and flexibility exercises is recommended. Although age in itself is not a limiting factor to exercise training, a more gradual approach in applying the prescription at older ages seems prudent. It has also been shown that aerobic endurance training of fewer than 2 d.wk-1, at less than 40-50% of VO2R, and for less than 10 min-1 is generally not a sufficient stimulus for developing and maintaining fitness in healthy adults. Even so, many health benefits from physical activity can be achieved at lower intensities of exercise if frequency and duration of training are increased appropriately. In this regard, physical activity can be accumulated through the day in shorter bouts of 10-min durations. In the interpretation of this position stand, it must be recognized that the recommendations should be used in the context of participant's needs, goals, and initial abilities. In this regard, a sliding scale as to the amount of time allotted and intensity of effort should be carefully gauged for the cardiorespiratory, muscular strength and endurance, and flexibility components of the program. An appropriate warm-up and cool-down period, which would include flexibility exercises, is also recommended. The important factor is to design a program for the individual to provide the proper amount of physical activity to attain maximal benefit at the lowest risk. Emphasis should be placed on factors that result in permanent lifestyle change and encourage a lifetime of physical activity.

Strength training: rationale for current guidelines for adult fitness programs

Strength training is an effective method for developing musculoskeletal strength and is often prescribed for fitness, health, and the prevention and rehabilitation of orthopedic injuries. Because strength training is an integral component in the comprehensive health program promoted by the major health organizations (eg, American College of Sports Medicine, American Heart Association, Centers for Disease Control and Prevention, US Surgeon General's Office), population-specific guidelines have recently been published. For the average adult beginning a strength training program, current research indicates that single-set programs performed a minimum of two times per week are recommended over multiple-set programs because they are less time-consuming, more cost-efficient, and produce most of the health and fitness benefits. The goal of this type of program is to develop and maintain a significant amount of muscle mass, endurance, and strength to contribute to overall fitness and health, not to optimize strength, power, and hypertrophy. By incorporating exercise prescription into patient counseling, clinicians can further increase their effectiveness as prevention-oriented healthcare providers.