View Full Version : Insulin Spike question...

07-12-2005, 05:25 PM
Now ive heard that after u lift u are supposed to eat carbs that are the high GI type to get a proper insulin spike. Well i was thinking would a pack of skittles do the trick better than anything else? They are high GI carbs and should cuz a pretty high insulin spike. Alright thanx alot for responding.

07-12-2005, 06:58 PM
Skittles contain table sugar (sucrose) which is a disaccharide containing glucose and fructose (approximately 50/50). I really do not think it is necessary to eat high GI carbs after your workout, as long as you have been taking in some kind of carb source before your workout. Eat clean foods and lift hard and you will be fine.

07-12-2005, 07:44 PM
BUT...if u do want something to spike your insulin and increase absorption PWO..look into some dextrose...its cheap and it spikes the insulin the greatest amount...

07-13-2005, 04:14 AM
BUT...if u do want something to spike your insulin and increase absorption PWO..look into some dextrose...its cheap and it spikes the insulin the greatest amount...

You don't really need a large insulin spike post workout, since a little insulin will go a long way, and after exercise insulin is not needed since glucose transport into the cell will happen regardless of whether insulin is present or not. Here are some related studies from that might be of interest.

Determinants of post-exercise glycogen synthesis during short-term recovery.

Jentjens R, Jeukendrup A.

Human Performance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, UK.

The pattern of muscle glycogen synthesis following glycogen-depleting exercise occurs in two phases. Initially, there is a period of rapid synthesis of muscle glycogen that does not require the presence of insulin and lasts about 30-60 minutes. This rapid phase of muscle glycogen synthesis is characterised by an exercise-induced translocation of glucose transporter carrier protein-4 to the cell surface, leading to an increased permeability of the muscle membrane to glucose. Following this rapid phase of glycogen synthesis, muscle glycogen synthesis occurs at a much slower rate and this phase can last for several hours. Both muscle contraction and insulin have been shown to increase the activity of glycogen synthase, the rate-limiting enzyme in glycogen synthesis. Furthermore, it has been shown that muscle glycogen concentration is a potent regulator of glycogen synthase. Low muscle glycogen concentrations following exercise are associated with an increased rate of glucose transport and an increased capacity to convert glucose into glycogen.The highest muscle glycogen synthesis rates have been reported when large amounts of carbohydrate (1.0-1.85 g/kg/h) are consumed immediately post-exercise and at 15-60 minute intervals thereafter, for up to 5 hours post-exercise. When carbohydrate ingestion is delayed by several hours, this may lead to ~50% lower rates of muscle glycogen synthesis. The addition of certain amino acids and/or proteins to a carbohydrate supplement can increase muscle glycogen synthesis rates, most probably because of an enhanced insulin response. However, when carbohydrate intake is high (>/=1.2 g/kg/h) and provided at regular intervals, a further increase in insulin concentrations by additional supplementation of protein and/or amino acids does not further increase the rate of muscle glycogen synthesis. Thus, when carbohydrate intake is insufficient (<1.2 g/kg/h), the addition of certain amino acids and/or proteins may be beneficial for muscle glycogen synthesis. Furthermore, ingestion of insulinotropic protein and/or amino acid mixtures might stimulate post-exercise net muscle protein anabolism. Suggestions have been made that carbohydrate availability is the main limiting factor for glycogen synthesis. A large part of the ingested glucose that enters the bloodstream appears to be extracted by tissues other than the exercise muscle (i.e. liver, other muscle groups or fat tissue) and may therefore limit the amount of glucose available to maximise muscle glycogen synthesis rates. Furthermore, intestinal glucose absorption may also be a rate-limiting factor for muscle glycogen synthesis when large quantities (>1 g/min) of glucose are ingested following exercise.

Regulation of GLUT4 protein and glycogen synthase during muscle glycogen synthesis after exercise.

Ivy JL, Kuo CH.

Department of Kinesiology, The University of Texas at Austin, 78712, USA.

The pattern of muscle glycogen synthesis following its depletion by exercise is biphasic. Initially, there is a rapid, insulin independent increase in the muscle glycogen stores. This is then followed by a slower insulin dependent rate of synthesis. Contributing to the rapid phase of glycogen synthesis is an increase in muscle cell membrane permeability to glucose, which serves to increase the intracellular concentration of glucose-6-phosphate (G6P) and activate glycogen synthase. Stimulation of glucose transport by muscle contraction as well as insulin is largely mediated by translocation of the glucose transporter isoform GLUT4 from intracellular sites to the plasma membrane. Thus, the increase in membrane permeability to glucose following exercise most likely reflects an increase in GLUT4 protein associated with the plasma membrane. This insulin-like effect on muscle glucose transport induced by muscle contraction, however, reverses rapidly after exercise is stopped. As this direct effect on transport is lost, it is replaced by a marked increase in the sensitivity of muscle glucose transport and glycogen synthesis to insulin. Thus, the second phase of glycogen synthesis appears to be related to an increased muscle insulin sensitivity. Although the cellular modifications responsible for the increase in insulin sensitivity are unknown, it apparently helps maintain an increased number of GLUT4 transporters associated with the plasma membrane once the contraction-stimulated effect on translocation has reversed. It is also possible that an increase in GLUT4 protein expression plays a role during the insulin dependent phase.

Publication Types:
Review, Tutorial

Dietary strategies to promote glycogen synthesis after exercise.

Ivy JL.

Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA.

Muscle glycogen is an essential fuel for prolonged intense exercise, and therefore it is important that the glycogen stores be copious for competition and strenuous training regimens. While early research focused on means of increasing the muscle glycogen stores in preparation for competition and its day-to-day replenishment, recent research has focused on the most effective means of promoting its replenishment during the early hours of recovery. It has been observed that muscle glycogen synthesis is twice as rapid if carbohydrate is consumed immediately after exercise as opposed to waiting several hours, and that a rapid rate of synthesis can be maintained if carbohydrate is consumed on a regular basis. For example, supplementing at 30-min intervals at a rate of 1.2 to 1.5 g CHO x kg(-1) body wt x h(-1) appears to maximize synthesis for a period of 4- to 5-h post exercise. If a lighter carbohydrate supplement is desired, however, glycogen synthesis can be enhanced with the addition of protein and certain amino acids. Furthermore, the combination of carbohydrate and protein has the added benefit of stimulating amino acid transport, protein synthesis and muscle tissue repair. Research suggests that aerobic performance following recovery is related to the degree of muscle glycogen replenishment.

Publication Types:
Review, Tutorial

Effect of different post-exercise sugar diets on the rate of muscle glycogen synthesis.

Blom PC, Hostmark AT, Vaage O, Kardel KR, Maehlum S.

Department of Physiology, National Institute of Occupational Health, Oslo, Norway.

The effect of repeated ingestions of fructose, sucrose, and various amounts of glucose on muscle glycogen synthesis during the first 6 h after exhaustive bicycle exercise was studied. Muscle biopsies for glycogen determination were taken before and after exercise, and every second hour during recovery. Blood samples for plasma glucose and insulin determination were taken before and after exercise, and every hour during recovery. When 0.35 (low glucose: N = 5), 0.70 (medium glucose: N = 5), or 1.40 (high glucose: N = 5) g.kg-1 body weight of glucose were given orally at 0, 2, and 4 h after exercise, the rates of glycogen synthesis were (mean +/- SE) 2.1 +/- 0.5, 5.8 +/- 1.0, and 5.7 +/- 0.9 mmol.kg-1.h-1, respectively. When 0.70 g.kg-1 body weight of sucrose (medium sucrose: N = 5), or fructose (medium fructose: N = 7) was ingested accordingly, the rates were 6.2 +/- 0.5 and 3.2 +/- 0.7 mmol.kg-1.h-1. Average plasma glucose level during recovery were similar in low glucose, medium glucose, and high glucose groups (5.76 +/- 0.24, 6.31 +/- 0.64, and 6.52 +/- 0.24 mM), while average plasma insulin levels were higher with higher glucose intake (16 +/- 1, 21 +/- 3, and 38 +/- 4 microU.ml-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of carbohydrate and milk-based beverages on muscle damage and glycogen following exercise.

Wojcik JR, Walber-Rankin J, Smith LL, Gwazdauskas FC.

Department of Human Nutrition, Foods, and Exercise at Virginia Polytechnic Institute and State University, Blacksburg 24061, USA.

This study examined effects of carbohydrate (CHO), milk-based carbohydrate-protein (CHO-PRO), or placebo (P) beverages on glycogen resynthesis, muscle damage, inflammation, and muscle function following eccentric resistance exercise. Untrained males performed a cycling exercise to reduce muscle glycogen 12 hours prior to performance of 100 eccentric quadriceps contractions at 120% of 1-RM (day 1) and drank CHO (n = 8), CHO-PRO (n = 9; 5 kcal/kg), or P (n = 9) immediately and 2 hours post-exercise. At 3 hours post-eccentric exercise, serum insulin was four times higher for CHO-PRO and CHO than P (p < .05). Serum creatine kinase (CK) increased for all groups in the 6 hours post-eccentric exercise (p < .01), with the increase tending to be lowest for CHO-PRO (p < .08) during this period. Glycogen was low post-exercise (33+/-3.7 mmol/kg ww), increased 225% at 24 hours, and tripled by 72 hours, with no group differences. The eccentric exercise increased muscle protein breakdown as indicated by urinary 3-methylhistidine and increased IL-6 with no effect of beverage. Quadriceps isokinetic peak torque was depressed similarly for all groups by 24% 24 hours post-exercise and remained 21% lower at 72 hours (p < .01). In summary, there were no influences of any post-exercise beverage on muscle glycogen replacement, inflammation, or muscle function.

07-13-2005, 06:03 PM
got it thanx..

07-13-2005, 08:00 PM
You don't really need a large insulin spike post workout, since a little insulin will go a long way, and after exercise insulin is not needed since glucose transport into the cell will happen regardless of whether insulin is present or not. Here are some related studies from that might be of interest.

nice. it's good to hear someone saying this! I think people over do it with straight dextrose. I do carbs before and like 1 fruit with my whey shake after workouts.

07-13-2005, 08:26 PM
Good post Bradley.

03-09-2009, 03:18 PM
I sip on dextrose in my Xtend while I lift and it works well. I have questioned this many times, and I agree with the studies. I once read that insulin sensitivity an increase up to 80% after exercise. This means you could conceivably cut out about half the carbs you're taking in and still get the same benefit. When I do the dextrose-xtend method, I only eat carbs from either oats or whole wheat after lifting. Sometimes, I'll have some fruit in my shakes. People who use "weight-gainers" are definitely overdoing it. Like Muscle Milk Collegiate... 90-something grams of straight carbs per serving is outrageous. Lineman get good results, though.