Slate CrossFit-360

Is High Intensity Training a More Effective Weight Loss Program

Hello Members:

My name is Karny Jacoby and I’m a urologist specializing in Female Pelvis Medicine and Reconstructive Surgery.  One of my passions is fitness and nutrition and that is why I helped to found Slate crossfit:  to promote fitness while having fun in a supportive community setting.  I thought I would start blogging about interesting journal articles that I find.  

It’s important to have fun exercising, but some of your non-crossfit friends or family may wonder why you are so addicted or what this movement is all about.  Lets call this “Slate Journal Club”.  I welcome your comments and contributions!  I also want to take this opportunity to thank each and every member for making Slate such a great community!

You know you are doing good things for your body at crossfit, but did you ever wonder if there is any data behind the “High Intensity Training” and “Sprint Interval Training” (SIT) movement?  I’ve pulled a few articles for you that are interesting and demonstrate the reduction in weight and fat composition, reduction of cancer incidence, and improved blood glucose. Lets unpack each of these studies…

This first study is actually a pilot study.  I was drawn to this paper because I think many women feel pressed for time and squeezed between their aging parents and their teenagers to give so much.  Here is a nice study demonstrating that with a limited HIIT program, postmenopausal women derived benefits including fat loss and improved body composition.

Meaningful weight loss in obese postmenopausal women: A pilot study of high-intensity interval training and wearable technology.
Grossman JA, Arigo D, Bachman JL. Menopause. 2017 Oct 30. doi: 10.1097/GME.0000000000001013. [Epub ahead of print]

 

Abstract
OBJECTIVE: 
Postmenopausal women cite lack of time as their primary barrier to exercise and related weight control behaviors. The purpose of this study was to address this barrier via testing the feasibility and initial outcomes of a short-duration/high-intensity interval training (HIIT)-based weight loss program among obese postmenopausal women, with descriptive comparison to an endurance-focused exercise program.

METHODS: 
A 16-week behavioral program incorporated (1) HIIT to limit time necessary to produce health benefits of exercise, and (2) wearable activity sensors to facilitate self-monitoring exercise. Participants (n = 11; MAge = 59 ± 5.33; MBMI = 32.0 ± 2.53 kg/m) were randomly assigned to HIIT or endurance exercise. Both groups followed a calorie-restricted diet, attended monthly in-person meetings, weekly weigh-ins and electronic check-ins to review behavioral skills, and monitored their exercise with a Fitbit ChargeHR. Adherence to exercise programs, assessed with the Fitbit sensor, was used to determine feasibility.

RESULTS: 
Participants in the HIIT group (6/6) adhered to their program, whereas 3 of 5 adhered to the Endurance program. Participants in the HIIT group lost twice as much weight as those in the Endurance group (8.7% vs 4.3% of initial body weight), and lost an additional 6 in. of body mass. In addition, only the HIIT group significantly changed fat mass, body mass index, and fat-free mass (Ps < 0.04).

CONCLUSIONS: 
These findings support the feasibility and potential effectiveness of HIIT for weight loss and body composition changes in obese postmenopausal women, and indicate that additional investigation of this approach is warranted to reduce postmenopausal chronic disease risk.

 

The second study is a huge meta analysis.  Running and cycling produced fat loss as well, but HIIT was more time efficient, and there was some evidence that it may be more effective but more studies are needed. (They always say that.)

 

Effect of High-Intensity Interval Training on Total, Abdominal and Visceral Fat Mass: A Meta-Analysis.
Maillard F, Pereira B, Boisseau N.
Sports Med. 2017 Nov 10. doi: 10.1007/s40279-017-0807-y. [Epub ahead of print] Review.

Abstract
BACKGROUND: 
High-intensity interval training (HIIT) is promoted as a time-efficient strategy to improve body composition.

OBJECTIVE: 
The aim of this meta-analysis was to assess the efficacy of HIIT in reducing total, abdominal, and visceral fat mass in normal-weight and overweight/obese adults.

METHODS: 
Electronic databases were searched to identify all related articles on HIIT and fat mass. Stratified analysis was performed using the nature of HIIT (cycling versus running, target intensity), sex and/or body weight, and the methods of measuring body composition. Heterogeneity was also determined RESULTS: A total of 39 studies involving 617 subjects were included (mean age 38.8 years ± 14.4, 52% females). HIIT significantly reduced total (p = 0.003), abdominal (p = 0.007), and visceral (p = 0.018) fat mass, with no differences between the sexes. A comparison showed that running was more effective than cycling in reducing total and visceral fat mass. High-intensity (above 90% peak heart rate) training was more successful in reducing whole body adiposity, while lower intensities had a greater effect on changes in abdominal and visceral fat mass. Our analysis also indicated that only computed tomography scan or magnetic resonance imaging showed significant abdominal and/or visceral fat-mass loss after HIIT interventions.

CONCLUSION: 
HIIT is a time-efficient strategy to decrease fat-mass deposits, including those of abdominal and visceral fat mass. There was some evidence of the greater effectiveness of HIIT running versus cycling, but owing to the wide variety of protocols used and the lack of full details about cycling training, further comparisons need to be made. Large, multicenter, prospective studies are required to establish the best HIIT protocols for reducing fat mass according to subject characteristics.

 

Here is a study discussing the benefits of strength promoting exercise in reducing cancer rates and cardiovascular mortality.  This study analyzed over 80,000 patients and came to the conclusion that, yes exercise reduced risk of developing both of those diseases.

 

Am J Epidemiol. 2017 Oct 31. doi: 10.1093/aje/kwx345. [Epub ahead of print]

Does strength promoting exercise confer unique health benefits? A pooled analysis of eleven population cohorts with all-cause, cancer, and cardiovascular mortality endpoints.

Stamatakis ELee IMBennie JFreeston JHamer MO’Donovan GDing DBauman AMavros Y.

Abstract

Public health guidance includes strength-promoting exercise (SPE) but there is little evidence on its links with mortality. Using data from the Health Survey for England (HSE) and Scottish Health Survey (SHS) from 1994-2008 we examined the associations between SPE (gym-based and own bodyweight strength activities) and all-cause, cancer, and cardiovascular disease mortality. Multivariable-adjusted Cox regression examine the associations between SPE (any, low/high volume, adherence to SPE guideline) and mortality. The core sample comprised 80,306 adults aged ≥30 years corresponding to 5,763 any cause deaths (681,790 person years). Following exclusions for prevalent disease/events in the first 24 months, participation in any SPE was favorably associated with all cause (0.77; 95% confidence interval: 0.69, 0.87) and cancer mortality (0.69; 0.56, 0.86). Adhering only to the SPE guideline of (≥2 sessions/week) was associated with all-cause (0.79; 0.66, 0.94) and cancer (0.66; 0.48, 0.92) mortality; adhering only to the aerobic guideline (equivalent to 150 minutes/week of moderate intensity activity) was associated with all-cause (0.84; 0.78, 0.90) and cardiovascular disease (0.78; 0.68, 0.90) mortality. Adherence to both guidelines was associated with all-cause (0.71; 0.57, 0.87), and cancer (0.70; 0.50, 0.98) mortality. Our results support promoting adherence to the strength exercise guidelines over and above the generic physical activity targets.

KEYWORDS: 

cancer; cardiometabolic; cardiovascular; epidemiology; mortality; physical activity; resistance training; strength promoting exercise; strength training

 

…and finally, we talk a lot about glycemic index of foods and controlling our blood sugar by what we eat or don’t eat…It’s nice to know that just by participating in crossfit, or any HIIT program, you can attenuate your blood sugar spikes.

 

Int J Exerc Sci. 2017 Nov 1;10(7):1076-1084. eCollection 2017.

Repeated Plyometric Exercise Attenuates Blood Glucose in Healthy Adults.

Barillas SR1Watkins CM1Wong MA1Dobbs IJ1Archer DC1Munger CN1Galpin AJ1Coburn JW1Brown LE1.

Author information

Abstract

Plyometric exercise is popular in commercial exercise programs aiming to maximize energy expenditure for weight loss. However, the effect of plyometric exercise on blood glucose is unknown. The purpose of this study was to investigate the effect of relatively high intensity plyometric exercise on blood glucose. Thirteen subjects (6 females age= 21.8 ± 1.0 yrs.; height= 163.7 ± 7.8 cm; mass= 60.8 ± 6.7 kg and 7 males age= 22.0 ± 2.6 yrs.; height= 182.3 ± 3.6 cm; mass= 87.4 ± 12.5 kg) volunteered to participate. Subjects completed two random conditions on two separate days, consisting of either five sets of 10 maximal effort countermovement squat jumps (SJ) with 50 seconds’ rest between sets or quiet sitting (SIT) for the time equated to the SJ duration (~4min). Immediately after each condition, subjects drank 75g of anhydrous glucose (CHO) in 100ml of water. Blood glucose measurements were taken via finger prick pre and immediately post SJ or SIT, and 5, 15, 30, and 60 min post. A 2×6 (condition × time) ANOVA revealed a significant interaction where SJ blood glucose was lower at 15 (114.0 ± 14.6 mg/dl) and 30 (142.1 ± 22.5 mg/dl) min compared to SIT (15min 130.8 ± 14.0 mg/dl and 30min 159.3 ± 21.0 mg/dl). The current plyometric protocol attenuated CHO-induced blood glucose at 15 and 30 min. This may be due to increased physiological stress applied to the muscles, thus increasing muscular glucose uptake.

KEYWORDS: 

Glycemic control; diabetes; interval training; jump

 

I hope you enjoyed these articles.  Let me know what you think about my “crossfit journal club”.  If you have an article you would like to share or discuss, or a particular topic of interest that you want me to write about,  contact me at Slate or post a comment on facebook.

 

Karny Jacoby, MD FPMRS