Almonds: Food for fitness

Engaging in exercise promotes a healthful lifestyle, but even when performed correctly, exercise causes fatigue and muscle damage. Recovery from exercise is important because it leads to muscle gain and improved fitness over time. A new study involving people who exercise occasionally (less than three times per week) demonstrated that snacking on almonds reduced feelings of fatigue and tension, increased leg and lower back strength during recovery, and decreased muscle damage during the first day of recovery.

David C Nieman, DrPH, FACSM, Professor and Principal Investigator, Human Performance Laboratory, Appalachian State University, led this novel research, supported with funding from the Almond Board of California. Dr Nieman's team wanted to see if an almond snack compared to a high-carbohydrate cereal bar snack would improve inflammation and recovery in adults engaging in 90-minute exercise sessions.

"What we found tells us definitively that almonds should be added to sports nutrition strategies to help people recover better from exercise," explained Dr Nieman. "Almonds are food for fitness. Carbs get most of the attention when it comes to fuelling for exercise, but almonds offer a nutrition package, including good unsaturated fats, the antioxidant vitamin E, and proanthocyanidins (class of polyphenols, which are protective compounds in plants) that help explain the beneficial outcomes in our study." One serving of almonds (28g) has 13 g of good unsaturated fat and only 1 g of saturated fat.

Study Design

In this trial, researchers included 64 healthy adults with an average age of 46 years. Participants were included if they exercised less than three (3) sessions per week. The experiment used a randomized, parallel group design, where treatment participants (n = 33) ate 57 g (2 ounces) almonds daily, split between morning and afternoon, for 4 weeks. Control participants (n = 31) consumed a calorie-matched cereal bar, also in split doses.

Participants submitted blood and urine samples and responded to mood and muscle-soreness questionnaires. Height, weight, and body composition were measured. Then, people in the study were instructed to perform muscle function tests (exercises), and once complete, they initiated the 4-week supplementation period—taking either almonds or cereal bars. At the conclusion of 4 weeks, participants submitted dietary intake records, blood and urine samples, and another set of questionnaire responses. Muscle function testing was repeated and then participants engaged in 90-minute eccentric exercise bouts comprising 17 different exercises.

Examples of eccentric exercise include slowly lowering a load to the floor, lowering into a squat, or lowering during a push-up. People in the study returned the following day to submit additional blood and urine samples and questionnaires as well as to perform additional physical fitness tests. Researchers assessed changes in plasma oxylipins, which are bioactive, oxidized lipids involved in the post-exercise inflammation response, and urinary gut-derived (from the large intestine) phenolics (antioxidants from plants), plasma cytokines, muscle damage biomarkers, mood states, and exercise performance.

Results

Almond consumers experienced:

• Reduced post-exercise fatigue and tension as well as higher levels of leg and lower back strength;

• Lower levels of serum creatine kinase, which is a marker of muscle damage, immediately and one day after exercise;

• Higher levels of the oxylipin (molecules that affect muscle function, recovery, and fat burn) 12,13-DiHOME and lower levels for oxylipin 9,10-DiHOME;

• Increased urine levels of phenolics derived in the large intestine (indicates consumption of polyphenols from almonds, and polyphenols are naturally occurring plant compounds that protect plants and may benefit human health);

• Some improvement to mood state following the intervention.

Of the oxylipin finding, Dr Nieman explained, "Oxylipins are normally generated during exercise. Some oxylipins are considered good 'players,' such as 12,13-DiHOME, which helps muscle burn more fat for fuel during exercise. Other oxylipins are pro-inflammatory and cause more harm than health. That's 9,10-DiHOME; a bad 'player.' This bad oxylipin can decrease muscle function, and it's elevated in certain disease states. Our almond consumers had a lower level of the bad 9,10-DiHOME compared to the control group." These oxylipin findings are exciting to Dr Nieman and will be of interest to the physical performance and sports nutrition communities. "The almond-related increase in 12,13-DiHOME and decrease in 9,10-DiHOME after vigorous exercise is an ideal outcome to support muscle function and recovery."

A limitation of the study is that it only included non-smoking participants without obesity who exercised occasionally; therefore, we cannot generalize the findings to other demographic and health status groups.

A one-ounce (28 g) serving of almonds provides 4 g (14% DV) fiber and 15 essential nutrients, including: 77 mg (20% DV) magnesium, 210 mg (4% DV) potassium, and 7.27 mg (50% DV), making them a perfect nutrient-rich snack to promote physical fitness.