Fitness News You Can Use

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Some of the latest fitness research all in one place, courtesy of Fitbits. This month's installment includes info on the Ab Slide, high intensity training for fat loss and bone density, and runner's injuries.

An Infomercial Product That Really Builds 6-Pack Abs

We are often quick to dismiss fitness devices sold from television infomercials as both gimmicky and useless. However, once in a while something appears that makes you think twice about the phrase "as seen on TV." In this case, researchers at the Mayo Clinic put the Ab Slide to the test against some common exercises previously found to effectively recruit the abdominals while minimizing the involvement of the hip flexors.

The Ab Slide, similar to the Ab Wheel, is a device used to perform the "rollout" exercise from the quadruped (birddog) position. Different from the Wheel, it offers a unique mechanism that assists the concentric effort.

In this study researchers measured EMG activity for the Rectus Abdominus (RA), External Oblique (EO), Internal Oblique (IO), and Rectus Femoris (RF) muscles. Exercises evaluated included while using the Ab Slide were the basic crunch, supine double leg thrust (SDLT), and side bridge.

The Ab Slide activated the RA and IO more than the other three exercises, and recruited the RF less than all but the side bridge exercise. Hence, the Ab Slide appears to be an exceptionally effective tool for training the abdominals.

Although EMG data was not collected for other muscles, participants did experience some discomfort in the shoulders and low back. Therefore, the Ab Slide may not be appropriate for people with low back pain or shoulder problems.

Youdas, J.W., et al (2008) An electromyographic analysis of the ab-slide exercise, abdominal crunch, supine double leg thrust, and side bridge in health young adults: implications for rehabilitation professionals. Journal of Strength & Conditioning Research. 22(6): 1939-1946.

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High Intensity Training Best for Reducing Visceral Body Fat

In July of this year we reported a study that found 16-weeks of high intensity interval training reversed Metabolic Syndrome or Syndrome 'X.' Of the factors contributing to metabolic syndrome, abdominal and visceral fat may be responsible for most of the associated increase in cardiac and metabolic risk. A recent study has found high intensity exercise to be most effective at reducing visceral fat, again decreasing risk factors for metabolic syndrome.

Researchers at Wake Forest University compared the effects of high intensity vs. low intensity exercise on abdominal visceral and subcutaneous fat deposition in middle-aged, obese women with diagnosed metabolic syndrome.

The high intensity group exercised above the lactate threshold (~85% HRR) three times weekly and below the lactate threshold on two additional days. The low intensity group exercised below the lactate threshold all 5 days. After 16 weeks participants were assessed for total abdominal fat, subcutaneous abdominal fat and visceral abdominal fat. In addition, factors associated with cardiometabolic risk, such as HDL-C, blood pressure, triglycerides and fasting blood glucose were measured.

The high-intensity group significantly lowered all factors associated with body fat whereas the low intensity group failed to exhibit any significant change. Most impressively, the high intensity group lost 4 times more overall body fat, 5 times more abdominal fat, and 3.5 times more visceral fat than the low intensity group. The high intensity group also experienced 50% greater improvement to VO2max compared to the low intensity group.

Irving, B.A. et al (2008) Effect of Exercise Training Intensity on Abdominal Visceral Fat and Body Composition. MSSE. 40(11): 1863-1872.

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Adding Insight to Injury for Runners

Injuries affect approximately 65% of all runners annually. Many of these injuries are considered overuse or chronic (e.g. plantar fasciitis, Achilles tendonitis/strains, knee pain/injury, etc.).

Interestingly, most of the information available on the factors responsible for injury is somewhat speculative since few studies have conclusively identified the mechanisms behind such injuries. In a recent study published in Medicine and Science in Sports and Exercise, researchers at Wake Forest University determined the relationship of some behavioral and physiological risk factors to knee joint stressesduring running.

Twenty previously uninjured runners were assessed on numerous variables including quadriceps and hamstring flexibility, quadriceps or Q-angle, and height and weight. Researchers performed gait analysis to evaluate stride lengths and to determine tibio-femoral (knee) compressive loads, performed isokinetic strength testing on the knee extensors, and participants completed questionnaires.

Of the variables tested, researchers reported that poor hamstring flexibility, increased body weight, higher weekly mileage and greater concentric muscle strength all contributed to greater knee stress.

Although previous studies have linked higher Q-angles to knee injuries in runners, the results of this and other studies question that link. In addition, previous studies have shown strength training reduces patello-femoral forces, but the results of this study indicate that concentric strength increases tibio-femoral compression. Further studies are necessary to determine the balance of strength factors necessary to optimize knee joint health in runners. Based on current research trends, it seems as though it would be wise for runners to improve hamstring flexibility and to achieve an ideal body weight prior to increasing weekly mileage.

Messier, S.P., et al (2008) Risk Factors and Mechanisms of Knee Injury in Runners. MSSE. 40(11): 1873-1879

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Circuit Training Ineffective to Build Bone Mass in Post-Menopausal Women

Previous studies have shown that high intensity strength training (HIST) increases bone mineral density in the femoral neck and lumbar spines in women. HIST refers to the use of heavier resistances, lower repetitions (12 to 6 RM or less), higher volume (3 or more sets per exercise), and/or greater muscle fatigue. Unfortunately, many women continue to avoid HIST because of the fear of "bulking up." Instead, women may tend to favor Circuit Training, which incorporates lighter resistances, higher repetitions and lower volumes. A recent study evaluated the potential of a typical Circuit Training (CT) protocol to increase BMD.

Twenty-eight postmenopausal women were split into Circuit Training, Strength Training and Control groups. Pre- and Post-assessments included body composition, VO2max, dynamic and isometric strength, and BMD.

Participants trained three times weekly. Over the 24-week program the CT group performed 2 sets of 15-20 reps per set progressing to 3 sets of 10-12 reps by the end. The ST group progressed to 3 sets of 6-8 reps. The CT group alternated exercises in supersets without any rest between sets. The ST group completed the sets consecutively with 2 minutes rest between sets. Participants used a mix of machines and free weights.

Both the ST and CT groups experienced similar improvements in VO2max and in time to exhaustion, whereas isometric strength gains were evident in the ST group only. Interestingly, there was a trend towards increased BMD in the ST group while the CT group was trending downward. It’s important to note that most studies on BMD have evaluated changes occurring after more than 9 months of training. This study was completed at 6 months.

Brentano, M.A., et al (2008) Physiological Adaptations to Strength and Circuit Training in Postmenopausal Women with Bone Loss. Journal of Strength & Conditioning Research. 22(6): 1816-1825.

Tags: Fitness News, Fitbits, Exercise Etc., fitness, Health, research, bone density, circuit training, runners, injuries, body fat, high intensity training, Ab Slide, abdominals