Sunday, July 27, 2008

FitBits - Fitness News

Here is the most recent issue of FitBits, from Exercise Etc.
July 15, 2008
Exercise ETC’s Review of Exercise Related Research

Compiled by Chris Marino, MS, CSCS
Director of Education, Exercise ETC

High Intensity Interval Training Reverses Metabolic Syndrome

High Intensity Interval Training (HIIT) is becoming somewhat of a phenomenon in fitness and conditioning. The only drawback to HIIT is that de-conditioned or untrained individuals may not tolerate relatively high intensities. Consequently, medical experts currently advocate progressively increasing intensity to reduce the risk of cardiovascular complication during exercise, improve compliance and minimize soft-tissue injury. The results of a recent study may challenge this philosophy.

Norwegian researchers reported that a 16-week HIIT program virtually reversed metabolic syndrome in a group of 28 participants. Metabolic syndrome represents a collection of symptoms that include impaired blood glucose control, along with obesity, a poor lipid profile and elevated markers of cardiovascular distress.

Participants were divided into 3 groups: HIIT, moderate continuous exercise (MCE), and control groups. The interval training group exercised at intensities greater than 90% HRmax, while the MCE group exercised at 70% HRmax. Both groups exercised 3 times per week and expended an equivalent amount of calories each workout.

Though both exercise groups lost similar amounts of body weight/fat, interval training proved better at improving blood pressure, insulin resistance, fasting blood sugars and HDL cholesterol. In addition, interval training produced more than twice the increase in VO2max compared to moderate-continuous exercise, 35% vs. 16%, respectively. In all, the interval-training group experienced a greater risk reduction for metabolic syndrome in less time than the MCE group.

Tjonna, A.E., et al (2008) Aerobic Interval Training Versus Continuous Moderate Exercise as a Treatment for the Metabolic Syndrome. A Pilot Study. Circulation. ePub July 7.

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Challenging the Conventional Lunge

The traditional forward lunge, performed with a long stride and an upright torso, has been advocated over other lunge variations because it is least strenuous on the low back and the forward knee. Unfortunately, this technique though safe is functionally deficient and may not produce desirable improvements in performance or function.

As part of the functional fitness movement many expert trainers have begun to incorporate greater hip flexion and consequently a more forward trunk position during the lunge: the "Glute Lunge." A recent study has supported the biomechanical claims that the Glute Lunge emphasizes the posterior muscles and may improve function better than the traditional lunge.

Researchers evaluated the motions, forces, and muscle activity in ten participants as they performed three lunge variations; 1) traditional lunge with the torso erect, 2) the Glute Lunge with the torso forward, and 3) a lunge with the torso extended.

As anticipated the Glute Lunge, which exhibits a greater peak hip flexion angle, recruited the glutes and hamstrings better than the traditional lunge, whereas the extended lunge did not change kinematics of the exercise.

This is the first study to compare the biomechanical variations between lunges. It is important to note that increased hip flexion during squatting or lunging does increase lumbar spine loading. Clients should be able to demonstrate adequate torso strength/stability and hip mobility prior to attempting the Glute Lunge.

Farrokhi, S., et al (2008) Trunk Position Influences the Kinematics, Kinetics, and Muscle Activity of the Lead Lower Extremity During the Forward Lunge Exercise. J Orthop Sports Phys Ther. 38(7):403-409

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Plyometrics May Impair Single Leg Balance

The use of explosive exercise techniques including plyometrics in fitness programs is on the rise. Recent research indicates that fast movements, explosive lifting, and jump training may improve function, performance and physiology better than traditional training methods. Unfortunately, implementing a power-training program does not come without risk.

A study published this month in the Journal of Sports Science reported that plyometric exercise might temporarily impair single leg balance, thus increasing risk for injury during the post-plyometric period.

Researchers had nine subjects complete 200 counter-movement jumps after which measurements were taken to assess calf muscle soreness, 20-second unilateral standing on a balance device, peak plantar flexion torque, and resting plantar flexion range of motion. Each measure was taken at baseline, 30-min post-exercise, 24-, 48-, and 72-hours.

In the end, single leg balance was significantly impaired for up to 24-hours following the plyometric exercise session; perceived soreness was increased and peak torque reduced. Trainers who integrate plyometrics should be cautious and adjust post-plyometric skill-development activities to minimize risk of injury.

Twist, C., et al (2008) The effects of plyometric exercise on unilateral balance performance. J Sports Sci. 12: 1-8.

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High-Protein Diet Does Not Inhibit Resistance Exercise Performance

Many nutritionists cite lack of energy for training and/or competition as a major disadvantage to high-protein diets when carbohydrates are reduced to less than 50% of daily caloric intake. Although evidence of reduced performance during endurance training exists, the effects of high-protein diets on anaerobic performance are less clear. Despite the lack of research, anaerobic athletes including resistance-trained individuals are more likely than endurance athletes to incorporate higher protein intakes to rebuild muscle following intense training.

Researchers in Greece recently reported the effects of a high-protein diet on strength, endurance and fatigue in 10 recreationally active women. Participants were assessed for isometric handgrip strength/endurance, and completed four sets of sixteen knee flexion/extension exercises at baseline and following 7 days each of two diets.

During the initial 7-day period participants followed a diet of 55% carbohydrate, 15% protein and 30% fat. The diet was changed to 30% carbohydrate, 40% protein, and 30% fat during the second week.

Heart rate response to training, arterial blood pressures, blood lactate and glucose levels, in addition to fatigue were assessed during training.

While consuming a high-protein diet, participants lost more weight and body fat than during the low-protein diet. Respiratory Exchange Ratio was also lower following the high-protein diet indicating greater use of fat for energy. No differences in any other measures were identified. Consequently, high-protein may be better for fat loss when compared to the traditionally recommended dietary composition.

Dipla, K., et al (2008) An isoenergetic high-protein, moderate-fat diet does not compromise strength and fatigue during resistance exercise in women. Br J Nutr. 100(2):283-6
In all fairness to the last study, that was still pretty high carbs. I appreciate that for medical people, 30% of calories from carbs seems low, but I regularly exist on 10-15% of calories from carbs and it has no impact on my workouts. In fact, since I began an ultralow carb intake more than 15 months ago, I have increased in strength more than ever before.

Clearly, every body is different, but carbs are NOT an essential part of the diet. We can make ketones from protein and fats and our bodies learn to use them for energy just as efficiently as it can use glucose. This is why the Atkins Diet works, but most people can't get through the adaptation period to living on ketones.

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