FitBits
Exercise ETC's Monthly Research Review
June 15, 2007
Compiled by Chris Marino, MS, CSCS
Director of Education, Exercise ETC
July Webinar Schedule and
other online events ... Click Here.
Glucose
Tolerance Testing
Helps Determine Best Eating Strategy
According to a recent study published in JAMA (Journal of the American Medical Association), using a glucose tolerance test to determine insulin levels may help to individualize nutrition recommendations for weight loss.
Researchers studied the effects of either a low-glycemic load (LGL) diet or low-fat diet (LF) on seventy-three obese adults age 18-35 over 6 months. Participants following the LGL diet consumed 40% of their food intake from carbohydrate (mostly low glycemic index foods), 35% fat, and 25% protein. The LF diet was composed of 55% carbohydrate, 20% fat, and 25% protein. Oral glucose tolerance testing and a blood lipid profile were performed on each participant prior to the intervention.
As expected, both groups experienced similar weight and body fat losses, however, researchers discovered that significant differences existed when accounting for insulin. Participants with higher baseline insulin levels lost nearly 10 pounds and 1.7% more body fat on the LGL diet vs. the LF diet. Weight and body composition changes were similar in participants with lower baseline insulin levels despite the intervention.
Blood lipid changes in both groups did not vary by insulin levels. As expected, the LGL diet increased HDL and lowered triglycerides to a greater extent than the LF diet, whereas the LF diet produced significant reductions in LDL.
The results of this study indicate that a simple glucose tolerance test may help determine whether individuals should be encouraged to eat fewer carbohydrates during weight loss. Because of the improvements to HDL and triglycerides, the authors recommend the LGL diet for weight loss. They further suggest that individuals who follow a LGL diet consume higher amounts of unsaturated fats to avoid increases in LDL cholesterol.
Ebbeling, C.B. et al (2007) Effects of a Low-Glycemic Load vs. Low-Fat Diet in Obese Young Adults. JAMA. 297: 2092-2102.
Cutting
Back on Endurance Volume
May Not Reduce Aerobic Capacity
Traditional endurance training models that emphasize very high volumes and moderate intensities, although practiced by nearly all elite, endurance athletes, are a primary factor in the high rate of chronic overuse injury in endurance sports. Consequently, research has sought alternative methods for optimizing endurance performance while reducing injury. Preliminary studies on high intensity resistance exercise and explosive or plyometric training have been promising.
One concern expressed by endurance athletes, is the effect that replacing endurance training volume with anaerobic training will have on maximal aerobic capacity; a determinant of endurance performance. A recent study published in the International Journal of Sports Medicine may help quell this fear. The researchers determined that max VO2 is unaffected when up to 20% of endurance training volume is replaced by explosive training.
Twenty-five 16-18 year old distance runners participated in the 8-week study. The participants were divided into two groups, one replacing ~20% of total endurance training volume with power/explosive training. Total training volume was equivalent between groups. The researchers completed pre- and post-assessment of top speed during anaerobic running and 30-m speed, top speed of aerobic running, maximal oxygen uptake, running economy, concentric and isometric leg extension, rate of force production in leg extension, and quadriceps size.
The explosive training group experienced small but significant changes in neuromuscular performance and anaerobic measures, including increased rectus femoris size. Increases in lean body mass or muscle hypertrophy is not often found during training of endurance athletes.
Although measures of aerobic performance were not improved, the fact that there was no decline is an important finding. Supplementing endurance training, and reducing endurance volume, by integrating more explosive and resistance exercise may reduce injuries by increasing muscle strength/size, increasing neuromuscular performance and reducing repetitive stress of movement.
Mikkola, J. et al (2007) Concurrent Endurance and Explosive Type Strength Training Improves Neuromuscular and Anaerobic Characteristics in Young Distance Runners. International Journal of Sports Medicine.
Eat
Your Cereal
For Post-Workout Recovery
Most dietitians agree that post-workout nutrition is essential to optimize recovery from exercise. An effective post-exercise beverage should include carbohydrate to replenish glycogen stores and stimulate insulin production, and protein to rebuild the tissues damaged during the workout. The recommended ratio of carbohydrate to protein ranges from 2:1 to 4:1 with research supporting each depending on the intensity of exercise, the individual and his/her goals.
Despite the variety in protein powders and sports drinks available many people find their taste abhorrent. That excuse is no longer acceptable, as a recent study found that using non-fat milk in post-exercise recovery is equally effective as sports drinks containing soy-protein mixtures. Furthermore, research presented at the 2007 ACSM national conference has found that cereal may be more effective method for optimizing recovery than some sports beverages.
Twelve athletes at the University of Texas participated in the study. Participants fasted for 12 hours and then cycled for 2 hours on two occasions, 5 days apart. Immediately after each exercise session the participants ingested either 100% whole-wheat flake cereal with skim milk or a common carbohydrate dense sports beverage.
Both groups experienced increased glucose and insulin levels. Interestingly, the cereal raised insulin significantly more and attenuated the rise in blood lactate better than the sports drink. These findings represent what could be an interesting future for post-workout nutrition; a move away from beverages and back to real food. As always, the most practical method will be the most effective.
Rauscher, Megan (2007) Healthy Cereal Tops Sports Drink after Workout. Reuters Health
Pre-habilitation
with Aerobic Exercise during Chemotherapy
Regular exercise is thought to prevent many types of cancer; however, few studies have examined the effects of exercise during cancer treatment. Although, the existing studies have shown aerobic exercise to have a positive impact on patient’ fatigue, functional capacity, maintenance of lean body mass, and quality of life during chemotherapy, some fear that adding exercise to treatment is one stress too many.
Researchers have recently questioned whether integrating exercise prior to chemotherapy may be both safer and more effective than initiating the two simultaneously. Thus, the body is permitted time to adapt to the initial stress of exercise before compounding the stress with chemotherapy. The results of a case study were presented in the Journal of Strength and Conditioning in June 2007.
A 42-year old female patient completed an evaluation of functional ability and fatigue levels one week prior to beginning chemotherapy. During that week she began a regular aerobic exercise regimen consisting of warm-up, aerobic walking (RPE 11-16), and cool-down. Aerobic walking duration was progressed from 15 to 35 minutes during the 9-week intervention.
The functional tests used included a 12-minute walk for distance, ascending and descending stairs for time, getting down and up from the floor, chair sit-to-stand for 30 seconds, and 30-seconds of arm curls.
Five of the seven functional tasks improved from ~23% to nearly 55% with insignificant improvement in the arm curl and chair sit-to-stand. Most important, by the end of 9 weeks the patient reported significant declines in fatigue achieving scores of 0 on all test areas.
Although this case study does not allow one to draw conclusions it serves as a preliminary investigation to guide future research, and supports the previous research that has documented benefits of exercise during chemotherapy.
Terson dePaleville, D. et al (2007) Effects of Aerobic Training Prior to and During Chemotherapy in a Breast Cancer Patient: A Case Study. The Journal of Strength and Conditioning Research. 21(2) 635-637.
July
Webinar Schedule
Our
Brand New "Guest Speaker" Series
Extended through July
Earn CEs from Your Home or Office!
Our Wednesday night Webinars have been so successful we have decided to extend them through July. What is a webinar? It is an opportunity for you to participate in a live workshop conducted over the internet. The program is presented in "real-time" with full interactivity with your instructor. For the month of July we are offering our brand new "Guest Speaker" series on Wednesdays from 7 – 9 PM ET (4 – 6 PM PT.) Here are the July topics:
July
11, 2007
Strength Training for Women
Heather Clawson, MD, CSCS
July
18, 2007
Strength Training Angles, Positions, Variations
Guy Andrews, MA, CSCS, *D, PES
July
25, 2007
Advanced Strength Training Techniques
John Kordich, M Ed, CSCS, *D
August
2, 2007
Designing Golf & Tennis Programs
Jeff Godin, Ph D, CSCS, HFPD
Each class is only $19.99 and is worth 2.0 / 0.2 CEs through most certifying organizations, including ACE, ACSM, AFAA, NSCA, NATA, NASM, ISSA, NETA and many more. For details, click on: http://www.exerciseetc.com/virtual.html
Tuesday
Nights, starting July 10, 2007
Designing Weight Management Programs
Ginger Patterson, Ph D, RD, LD
For details, click on: http://www.exerciseetc.com/virtual.html
Monday
Nights, starting July 30, 2007
ACE Personal Trainer Exam Review Class
Trish Muse, MPT, CSCS
For details call 1-800-244-1344 or click on:
http://www.exerciseetc.com/pt_sched.html#onlineschedule
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