Many personal trainers design anaerobic workouts for their clients—it is an innovative strategy that helps many people reach their goals. Competitive athletes have been training anaerobically for years. Bu these types of programs also offer recreational exercise enthusiasts challenge, variety and unique physiological adaptations. Common elements of an anaerobic workout include intervals, sprints, repeated sprints and multiple-sequence exercise combinations performed at higher intensities with shorter duration (Bishop, Girard & Mendez- Villanueva 2011).

Anaerobic conditioning involves motor unit activity; metabolic factors (e.g., phosphocreatine recovery and hydrogen ion buffering); substrate use (e.g., the rate of phosphagen, glucose and glycogen liberation of ATP); and force-speed patterns that affect muscle activation and recruitment (Bishop, Girard & Mendez-Villanueva 2011; Plisk 1991). ThThus, anaerobic training results in specific neurological, metabolic and muscular adaptations.

This article provides an overview of the scientific theory and physiology underlying the bioenergetic systems emphasized in anaerobic conditioning and introduces program design guidelines and ideas.

Biological Energy Used for Anaerobic Training

All exercise programs—and life itself, for that matter—require that cells be able to provide sufficient energy for the demands placed on them. When the food we eat is broken down, it does not directly release cellular energy for life and physiological work. It is the breaking of chemical bonds in food that releases the energy to produce and utilize adenosine triphosphate (ATP), a high-energy molecule (McArdle, Klatch & Klatch 2010). All living organisms use ATP as their primary energy currency. Cells metabolically split a phosphate group from ATP molecules (as needed), releasing the energy used for life functions and exercise needs (see Figure 1). When one or both of the two terminal phosphate-oxygen molecules attached to ATP are detached, energy is released. Each phosphate group is separated from ATP in the presence of water (a process called hydrolysis), and approximately 7.3 kilocalories of usable energy are immediately liberated to the cell to perform work (McArdle, Klatch & Klatch 2010). Interestingly, ATP carries just the right amount/ level of energy for most biological reactions.

Figure 1

Each muscle cell stores a limited quantity of ATP and requires a lot of energy to perform muscular work. Thus, ATP is constantly being regenerated from two anaerobic systems and one aerobic energy pathway. The anaerobic energy systems include the phosphagen system and anaerobic glycolysis.

Figure 2

The Phosphagen System: Immediate Energy

Phosphocreatine (PC) stored in muscle cells has a lot of energy, just like ATP. However, when the phosphate group is broken off in PC (see Figure 2), the energy liberated synthesizes ATP in a coupled reaction in the presence of adenosine diphosphate (ADP).

Because PC and ATP contain phosphate groups, they are referred to as the phosphagen energy system. This system is associated with energy production needs that last several seconds at high intensity levels, such as during sprints or near-maximal muscle contractions. PC is re-formed from inorganic phosphate (Pi) and creatine from the energy released from ATP. This re-formation process occurs during exercise recovery. Thus, during high-intensity exercise there is a limit to the amount of work a client can do because the muscle has limited supplies of PC. The intensity is too rapid for PC to be regenerated.

In summary, the phosphagen energy system provides the most rapid delivery of ATP because

  1. it does not require oxygen for any of the reactions;
  2. ATP and PC are stored (in limited amounts)within the contractile proteins of muscle; and
  3. few chemical reactions are needed to break off the phosphate groups from PC and ATP for the cell’s energy needs.

The Anaerobic Glycolytic Energy System

Carbohydrates are either converted to glucose for immediate energy needs or stored in the liver and muscle as glycogen (McArdle, Klatch & Klatch 2010). Glycogen is the linkage of many glucose molecules by glycosidic bonds. With the help of a specialized enzyme, glycogen phosphorylase, sequential glucose molecules may be removed from the glycogen and sent to the active muscles for further breakdown to produce ATP in a process called glycolysis (McArdle, Klatch & Klatch 2010) (see Figure 3).

As the name implies, anaerobic glycolysis is the splitting of glucose in the absence of oxygen during any of the breakdown reactions (McArdle, Klatch & Klatch 2010). Glycolysis, which begins with glucose, occurs in the muscle cell’s cytosol (cellular fluid also referred to as sarcoplasm). Anaerobic glycolysis provides ATP at a very rapid rate during near-maximal to maximal exertion lasting up to 2 minutes. Pyruvate is the final product of glycolysis, and in the absence of oxygen, it is converted to lactate. Although once considered a “dead-end” metabolite, lactate is now recognized as a valuable fuel substrate for heart and skeletal muscle (Plowman & Smith 2011). Lactate production coincides with the release of hydrogen ions (protons released from the splitting of ATP), which make the muscle cells’ environment more acidic. This cellular acidosis inhibits energy production and contributes to muscular fatigue. Therefore, lactate production does not cause acidosis; it just accompanies it.

Figure 3

The aerobic metabolism (see Figure 3) of carbohydrate involves the complete breakdown of glucose and glycogen with oxygen in the cell’s mitochondrion. The following pathways are involved:

  • the conversion of pyruvate to acetyl coenzyme A (ace-tyl-CoA)
  • the citric acid (TCA) cycle, or Krebs cycle, which is a series of chemical reactions in the mitochondrion that break down all organic fuel molecules
  • the electron transport chain, a sequence of electron carrier proteins that shuttle electrons from the organic fuel molecules to make ATP

Glycolysis pathways with sufficient oxygen present largely support endurance-type exercise (Plowman & Smith 2011).

Designing Anaerobic Training Programs

Remarkably, little research has been published to summarize the best training methods for anaerobic fitness. Researchers, coaches and exercise professionals have consistently targeted specific muscles or movement patterns for athletic races or events and have designed progressively increasing training strategies (i.e., using the overload principle). Fortunately, one of the most comprehensive, practical, evidence-based articles on anaerobic metabolic conditioning—by Plisk (1991)—provides splendid guidance and theory-driven direction for over all anaerobic program design. Plisk focuses on the following key areas: repetition intensity/duration, exercise-to-relief ratio, total exercise volume, training frequency, program duration, value of resistance training design, and training progression.

Repetition intensity/duration. Exercise intensity is considered a primary stimulus for anaerobic conditioning. Plisk notes that the phosphagen energy system and glycolytic-glycogenolytic pathways are best trained with exercises that increase intensity or speed (without compromising technique) rather than with longer-duration exercises. These energy systems dominate the first 120 seconds of exercise. Personal trainers use heart rate monitoring as a relative intensity guideline for how hard a cardiovascular exercise is being performed. With anaerobic conditioning, however, heart rate measurement is a poor indicator of exercise intensity, as neurological factors elevate heart rate disproportionately during anaerobic exercise. Exercises are often performed over a continuum of somewhat hard, near-maximal and maximal intensities. Plisk suggests that trainers focus on exercise quality (not quantity) and sufficient intensity for eliciting optimal training responses and adaptations.

Exercise-to-relief ratio. Bishop, Girard & Mendez-Villanueva (2011) assert that with repeated exercise bouts (e.g., sprints), phosphocreatine restoration (or resynthesis) is of great concern because it is the most rapid supplier of ATP for the contracting muscle proteins during anaerobic training. The authors affirm that complete phosphocreatine resynthesis takes up to 3 minutes after high-intensity exercise. For repeated bouts, Plisk suggests using a 1-to-4 exercise-to-relief ratio initially and then, over a period of weeks, tapering to a 1-to-2 or 1-to-1.5 ratio. Therefore, if an exercise takes 30 seconds to complete, initially the 1-to-4 exercise-to-relief ratio indicates that the client should recover for at least 120 seconds and then repeat the exercise. Athletes may perform multiple sets of exercise-to-relief bouts. For this strategy, Plisk recommends allowing a minimum of 2 minutes between sets for near-complete phosphagen resynthesis.

Interestingly, Bishop, Girard & Mendez-Villanueva note that an active recovery, such as walking or jogging, is optimal for enhancing phosphocreatine resynthesis and for clearing the buildup of hydrogen ions (from the splitting of ATP). The same authors explain that persons with higher aerobic fitness levels are able to resynthesize phosphocreatine more effectively, thus emphasizing a unique benefit of cardiovascular exercise (for improving anaerobic performance).

Total exercise volume. Evidence-based guidelines for anaerobic conditioning regarding total workout volume (i.e., the number of repetitions, sets and circuits) have yet to be elucidated. Coaches and researchers have explored parameters for competitive athletes (for specific events), yet general guidelines are currently not established. Plisk concludes that “until more information is available, manipulation of this variable is best left to the discretion of the practitioner.”

Training frequency. Anaerobic training frequency for athletes may be quite different from what is appropriate for recreational clients. In view of previously established parameters to train for quality and not quantity, Plisk suggests that trained individuals take 2–3 rest days per week. This should provide sufficient recovery between workouts while preventing overtraining.

Program duration. Consistent anaerobic conditioning has been shown to meaningfully improve several physiological components—including oxidative capacity, phosphocreatine recovery, hydrogen ion buffering, and muscle activation and recruitment—in as little as 5 weeks (Bishop, Girard & Mendez-Villanueva 2011). This information can be useful to personal trainers wishing to educate clients about how long it will take to start realizing changes from anaerobic training.

Value of resistance training. Some clients want to improve anaerobic performance in recreational activities such as short races. Research indicates that maximal strength improvement is less favorable with resistance training programs. Resistance training that includes a high metabolic load—such as sets of 10–20 repetitions maximum (a person can complete 20 repetitions but not 21)—have proved most optimal (Bishop, Girard & Mendez-Villanueva 2011). Plisk points out that many sprint-type and explosive competition sports involve a lot of ballistic, stretch-shortening, eccentric contractions; he therefore recommends resistance training involving controlled eccentric con- tractions. Personal trainers may wish to incorporate a 1-second concentric phase with a 4-second eccentric phase for many of the target exercises and movements they select.

Training progression. Periodized training is considered a superior method of training for developing peak performance in athletes (Turner 2011). The training consists of a sequential, structured exercise program that varies several meaningful training variables (load, rest, repetitions, sets, recovery, exercise choice, exercise order, etc.) into blocks of training times. Periodized programs can last several weeks to months and even up to a year. For athletes, the training progression typically follows an off-season, preseason and in-season progression.

In the off-season, the goal is to build a physiological foundation that develops endurance, strength and power for the target athletic goals. The preseason is usually 8–12 weeks of training prior to competition, where athletes attempt to maximize anaerobic conditioning specific to the event. In-season training usually emphasizes skill development and competition preparation. Plisk notes that owing to individual goals and differences, these training phases may have overlapping characteristics, as practitioners are always concerned with finding the ideal training stimulus while avoiding overtraining and undertraining.

From Theory to Practical

The four circuits below give personal trainers some practical ways to include anaerobic training into personal training sessions. The following recommendations apply the research and physiological understandings of the metabolic, neural and muscular aspects of anaerobic training.

  • Perform all exercises for 20–30 seconds at a controlled exercise pace.
  • Progress from exercise to exercise as opposed to resting and repeating each exercise.
  • Choose an exercise intensity appropriate to the client’s fitness level and goals, from somewhat hard, to hard, to near-maximal exertion.
  • After completing a circuit, do an active recovery—such as brisk walking, light cycling or jogging for 2–3 minutes—and then repeat the circuit. Individualize the total number of circuits for each client.
  • Regularly change the exercise order and incorporate other moves to offer a variety of neuromuscular stimuli.
  • To make each circuit aerobic, add 2:30 minutes of walking, jogging or cycling (at 65%–75% of heart rate maximum) after each exercise.
  • To make each circuit a weight-interval workout, incorporate 30 seconds of sprinting on a treadmill or 30 seconds of high-intensity cycling after the second and fourth exercises in the circuit, followed by 3 minutes of active recovery at a self-selected intensity.
  • Intersperse the anaerobic training with the client’s regular training programs.
  • Complete some type of anaerobic training two to three times per week.

Sample Circuits


Use the guidelines above when implementing the following anaerobic circuits with your clients.

Jump Lunge

Jump Lunge

Start in lunge (split-squat) position and jump in the air, switching legs each time.

Medicine Ball Slam

Medicine Ball Slams

Hold medicine ball overhead and slam it onto floor, alternating each side.

Kettlebell Floor Press

Kettlebell Floor Press

Lie on floor holding kettlebell with both hands. Press kettlebell straight up toward ceiling.

Meadow Row

Meadows Row

Hinge forward at hip, place hands on hip for support and begin rowing exercise with end of weighted barbell or with dumbell or kettlebell. Alternate sides.

Plate Pushes

Plate Pushes

Place hands on top of barbell plate and assume push-up position. Driving with legs, push plate across floor.


Kneeling Kettlebell Press

Kneeling Kettlebell Press

Kneel with hips extended and core engaged. Hold kettlebell “bottoms up” and complete single-arm presses. Switch sides.

Side Plank with Single Arm Band Row

Side Plank With Single-Arm Band Row

Begin in side plank position with supporting elbow in line with shoulder, core engaged. Extend top arm in front of body and perform single-arm row with exercise band or tubing anchored securely. Do both sides.

Stir The Pot

Stir The Pot

Place elbows on stability ball, body in plank position. Perform continuous circles in both directions, keeping core engaged.

Cable Face Pulls

Cable Face Pulls

Securely anchor resistance tubing (or use cables) and pull handles directly toward face, separating hands, elbows high.

Goblet Squats

Goblet Squat

Grab dumbbell or kettlebell, and hold it next to chest while sinking hips into squat. Use good form throughout.


Side-Rotation Medicine Ball Wall Throws

Side-Rotation Medicine Ball Wall Throws

Hold medicine ball and stand 6-10 feet from wall, arms extended. Rotate torso as you throw medicine ball into wall. Retrieve and repeat; alternate sides.

Plate-Pinch Walk And Carry

Plate-Pinch Walk and Carry

Squeeze and hold barbell plate with fingers and thumb. Walk for timed period and switch arms. If it feels like weight is going to drop, slowly bend knees—while keeping back straight—and put plate on floor.

Double Arm Row

Double-Arm Row

With feet shoulder-width apart and core engaged, perform double-arm row with kettlebells or dumbbells.

Kneeling Kettlebell Press

Alternating Reverse Lunge To Single-Arm Press

Step backward and lower body until back knee is ~2-5 inches from floor. Then, press dumbbell directly over shoulder and lower. Return to start position and alternate legs. Repeat press with other arm.

Side Plank with Single Arm Band Row

Kettlebell Overhead Walks

Press and hold kettlebell over head. Walk at brisk pace for prescribed time. Switch arms and repeat.


Double Kettlebell Deadlift

Double Kettlebell Deadlift

Hold kettlebell in both hands, engage core, and perform deadlift with slightly bent knees as you squeeze gluteals and extend hips.

Renegade Rows

Renegade Row

Place two dumbbells on floor about shoulder-width apart in push-up position. Spread legs slightly for better balance. Perform alternating single-arm rows while holding plank.

Long Lever Plank

Long-Lever Plank

Begin prone on floor, feet together, spine and pelvis neutrally aligned, core engaged. Move into forearm plank, but with elbows angled at approximately 100 degrees. Hold for prescribed time.

Side-Rotation Medicine Ball Wall Throws

Alternating Lunge And Overhead Triceps Extension

Keep dumbbells at shoulders, step forward to lunge, and hold. Perform overhead triceps extension. Step back to start position, and complete sequence with other leg.

Plate-Pinch Walk And Carry

Kettlebell Swings

Place feet shoulder-width apart, knees flexed, eyes forward. Drive hips forward as you swing kettlebell to shoulder height.

Circuit Training Study Offers Insights Into Anaerobic Conditioning

Circuit weight training, a form of anaerobic conditioning, and interval training have gained popularity because they maximize training results in a time-efficient manner. This concept is massively attractive to a society of time-crunched exercisers, and for good reason.

Traditional circuit weight training (TRAD) typically includes a specific number of weightlifting exercises with short rest periods between sets. TRAD has been shownto increase muscular strength and endurance, but it has little effect on aerobic capacity. Aerobic circuit weight training (ACWT) is designed similarly to circuit weight training, but the rest periods involve an aerobic component. This method has been shown to increase aerobic capacity and also benefit muscular fitness. Circuit weight-interval training (CWiT) aims to combine TRAD with high-intensity interval training (HiiT). HiiT entails short bouts of high-intensity exercise with predetermined rest periods and effectively improves aerobic capacity.

With so many promising options, which circuit training mode is most effective? Skidmore and colleagues (2012) set out to answer that question by comparing TRAD, ACWT and CWiT.

The Study: Skidmore et al. 2012

Eleven women averaging34 years old participated in the study. All subjects were required to have trained aero- bically for 30 minutes 3 days per week for at least 6 months. Participants who were pregnant and/or had spinal and/or lower-limb musculoskeletal injuries within the previous 6 months were excluded.

After the researchers had taken baseline measurements, participants completed the TRAD, ACWT and CWiT circuits—on separate days—in order to familiarize themselves with the tempo of each program. Subjects then completed each of the protocols (see Table 1) again on different days. Researchers built in at least 72 hours between sessions to ensure adequate recovery time. Each program consisted of a 5-minute cycle warm-up at 60%-70% of HRmax, followed by the same resistance training stations, labeled as A1, B2 and C3 (see Table 2). Participants completed 3 sets of 13 repetitions for each strength exercise.

TRAD involved 30 seconds of weightlifting and 30 seconds of rest between sets. ACWT involved the same amount of time lifting weight, but rest periods were shortened to 15 seconds. Researchers also added 2:30-minute cycling bouts at 65%-75% of HRmax between stations. in CWiT, the times allowed for weightlifting and rest between sets were the same as in ACWT, but subjects performed a 30-second maximal-effort cycle sprint followed by a 3-minute cool-down (pedaling with no resistance on bike) between each station. Each program ended with a 5-minute cool-down (easy pedaling on a cycle). The TRAD workout took 38 minutes to complete; the other two each took 41 minutes.

Variables Measured and Results

The three exercise intensity variables measured in this study were blood lactate (BLA), rating of perceived exertion (RPE) and heart rate (HR). During the TRAD workout, researchers measured the variables after subjects completed each resistance training station (A1, B2 and C3); during ACWT and CWiT, measurements took place after each cycling bout (2:30-minute ride or 30-second sprint).


Results showed that BLA increased over the course of each workout; however, concentrations were significantly greater at each time point during CWiT compared with TRAD and ACWT. BLA was significantly greater in ACWT than it was in TRAD after the final time point (C3) of the workout. At the endof the workout, BLA in CWiT was 132% greater than in TRAD and 60% greater than in ACWT.

Like BLA, HR rose throughout each protocol, but CWiT elicited significantly greater HR than ACWT and TRAD at each point during the exercise session. in ACWT, HR was significantly greater than in TRAD after the first time point (A1). After workout completion, HR was 14% greater for CWiT than for ACWT and TRAD.

Finally, RPE rose through- out the course of each protocol, but RPE was significantly greater at all time points during CWiT than it was during TRAD and ACWT. interestingly, RPE was also greater at all time points during ACWT than it was during TRAD. RPE measurements after completing the CWiT workout were 38% and 8% greater than TRAD and ACWT, respectively.

Summary Thoughts

Any of these three circuit weight-training protocols follow a pattern of increasing exercise intensity. However, for recreationally active and healthy populations looking to achieve an extremely effective time-efficient workout, CWiT appears to be superior to TRAD and ACWT. if clients cannot perform maximal sprints due to physical limitations or personal choice, ACWT is an effective option, as it provides both an aerobic and an anaerobic stimulus.


Bishop, D., Girard, O., & Mendez-Villanueva, A. 2011. Repeated-sprint ability–part II: Recommendations for training. Sports Medicine, 41 (9), 741-56.
McArdle, W.D., Katch, F.I., & Katch, V.L. 2010. Exercise Physiology (7th ed.). Philadelphia: Wolters Kluwer.
Plisk, S.S. 1991. Anaerobic metabolic conditioning: A brief review of theory, strategy and practical application. Journal of Applied Sport Science Research, 5 (1), 22-34.
Plowman, S.A., & Smith, D.L. 2011. Exercise Physiology for Health, Fitness, and Performance (3rd. ed). Philadelphia: Wolters Kluwer.
Skidmore, B.L., et al. 2012. Acute effects of three different circuit weight training protocols on blood lactate, heart rate, and rating of perceived exertion in recreationally active women. Journal of Sports Science and Medicine, 11, 660-68.
Turner, A. 2011. The science and practice of periodization: A brief review. Strength and Conditioning Journal, 33 (1), 34-45.
Zuhl, M., & Kravitz, L. 2012. HIIT vs. continuous endurance training: Battle of the aerobic titans. IDEA Fitness Journal, 9 (2), 34-40.

Len Kravitz, PhD

Len Kravitz, PhD is a professor and program coordinator of exercise science at the University of New Mexico where he recently received the Presidential Award of Distinction and the Outstanding Teacher of the Year award. In addition to being a 2016 inductee into the National Fitness Hall of Fame, Dr. Kravitz was awarded the Fitness Educator of the Year by the American Council on Exercise. Just recently, ACSM honored him with writing the 'Paper of the Year' for the ACSM Health and Fitness Journal.

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