Energy Systems: Comparing and Contrasting Aerobic and Anaerobic Conditioning

by Joseph Giandonato, PhD, MBA, CSCS

Introduction

Human movement is facilitated by a torrent of chemical reactions in which stored energy is mobilized, released, and converted to mechanical work that comprises muscular contraction. Stored energy is found in two predominant forms: glycogen within muscles and the liver and fatty acids encompassing triglycerides within muscles and fat cells. The body also has a negligible amount of readily available adenosine triphosphate (ATP), a high-energy phosphate compound which facilitates muscular contraction, when needed to support survival functions, such as the body’s catecholamine mediated “fight or flight” response. In addition to storing glycogen and triglycerides, muscles contain phosphocreatine, which is one metabolic step removed from producing ATP. ATP is constructed from an adenine base and three phosphate groups attached to ribose, a naturally occurring simple sugar. The formation of ATP transpires through the linkage of adenosine diphosphate (ADP) and inorganic phosphate (Pi) yielding a high energy bond. During the conversion of chemical energy to mechanical work, the ATP is bound to myosin and hydrolyzed back into ADP and Pi by ATPase enzymes located on myosin filament at which point it is primed to bind to actin to initiate muscular contraction. ATP is manufactured primarily by three distinct energy systems within the body: phosphagen (or anaerobic alactic energy system), glycolytic (or anaerobic lactic energy system), and oxidative (or aerobic energy system). These energy systems and their attendant ATP production capacity can be improved through concerted, evidence-based conditioning programming.

Anaerobic Conditioning

The term anaerobic stems from a Latin root word and means “without air”. The body’s anaerobic energy system does not require oxygen to produce ATP. Instead, ATP is produced when a phosphate group is donated from the body’s ATP reserves along with its bond energy from the breakdown of phosphocreatine to ADP to facilitate high intensity muscular efforts, such as throwing, jumping, and accelerating to peak horizontal velocity, or maximum sprint speed. Due to the finite amount of readily available ATP, high intensity muscular work cannot be prolonged. ATP is also produced from the oxidation of usable glucose to form two molecules of pyruvate or lactate. This process is known as glycolysis and is characterized by the transfer of bond energy from glucose to rejoin Pi to ADP. 

The premise of anaerobic conditioning is to sustain the transfer of bond energy from glucose to rejoin Pi to ADP continuously to facilitate repeated high intensity muscular efforts that are critical to performance in a range of individual, team sport, and track and field training and competition. The ability to recover and regenerate ATP via the anaerobic energy system is known as repeat sprint ability (Turner & Stewart, 2013) or more commonly known as anaerobic work capacity. Athletes with a greater work capacity can compete longer, train more frequently and with greater volume, and are able to recover more quickly than athletes with lessened work capacity. Fortunately, anaerobic work capacity can be developed through anaerobic conditioning. Adaptations to anaerobic conditioning include reduced blood lactate concentrations, increase in maximal blood lactate concentrations and improved lactate buffering capacity, significant elevations in glycolytic enzymes, and prompting a transition from type II fibers to a more glycolytic subtype (Hoffman, 2014).

On the surface, one may assume that anaerobic conditioning consists exclusively of sprint work. And while some anaerobic conditioning training modalities comprise sprint work, anaerobic capacity can be developed through a variety of means. However, prior to formulating an anaerobic conditioning program, strength and conditioning professionals should first conduct a needs analysis and consider the sport or competitive event and accompanying tactical, technical, and logistical nuances. For instance, a football team whose offense runs a read-option with a spread formation and often goes no huddle will require a vastly different approach to anaerobic conditioning in comparison to a football team with an offense that employs a West-Coast scheme that is predicated upon shorter completions and huddles between every play. Common forms of anaerobic training modalities include: interval sprints, Fartlek (or short bursts of sprints interspersed with jogging), repetition sprints (or maximum number of sprints for prescribed cumulative distance), and rolling sprints, in which athletes run slowly around a track and the last athlete sprints to the front. Anaerobic conditioning can also be improved by training at a 1:1 work-to-rest ratio (Burke et al., 1994) and strongman training (Woulfe et al., 2014).

Aerobic Conditioning

Conversely, the body’s aerobic energy system relies on the presence of oxygen for ATP production and consists of two metabolic pathways: the Krebs cycle and the electron transport chain. The Krebs cycle oxidizes substrates, including fat, using two hydrogen carrying molecules: nicotinamide adenine dinucleotide (NAD) and flavin adenine dinucleotide (FAD). The electrons in the hydrogen molecules are then passed through the electron transport chain as a final step in providing energy for aerobic production of ATP in the mitochondria. 

Through regular aerobic conditioning, also known as endurance training, the body’s ATP production capacity can increase as can cardiac output, stroke volume, blood volume and hemoglobin concentration, and attendant decreases in resting heart rate and blood pressure (Hoffman, 2014). Additionally, increases in mitochrondrial density and capillary number, oxidative enzymes, reliance on stored fat as energy, and myoglobin content are noted following regular aerobic conditioning (Hoffman, 2014; Powers & Howley, 2018).

In a performance training context, regular endurance training can increase lactate threshold by delaying the onset of blood lactate accumulation, increase maximal aerobic capacity, or VO2max and is capable of tendering improvements in exercise economy. Among endurance athletes, race or event performance is predicated upon the tripartite lactate threshold, VO2max, and exercise economy vectors. For athletes who participate in individual, team sports, and or track and field events, regular performance in lower intensity steady state endurance training can improve body composition, improve intra- and inter- session recovery, and influence parasympathetic domain. To mitigate a potential interference effect, or decrement in anaerobic performance, aerobic endurance and resistance training sessions should be interpolated by a 4-to-8-hour recovery interval (Panissa, 2022). Lower intensity and shorter duration aerobic training sessions should be considered to temper the magnitude of interference (Wilson, 2012).

Programming Considerations for Individual and Team Sport Athletes and Track and Field Athletes

The demands of individual and team sport athletes are highly varied in comparison to track and field athletes who may compete in as few as one event at higher levels of competition. The requisite fitness qualities and biomotor skills needed to participate in individual or team sports at an amateur or professional level are greater than those who compete in track and field events. As such, individual and team sport athletes may devote only one to two days per week dedicated to developing linear speed, whereas sprinters may focus on speed work multiple days throughout the week, in the form of dedicating certain days to acceleration, honing technique and front-end mechanics, and concentrating on the drive phase. Due to the wider spectrum of biomechanical demands associated with individual and team sports and competing demands such as frequent practices and other preparedness emphases, athletes are not able to perform as much sprint work as sprinters. Additionally, repeat sprint ability and the ability to regenerate ATP is of greater importance among athletes than sprinters.

Conclusion

In summary, strength and conditioning professionals should be cognizant of the biomechanical and bioenergetic demands associated with individual, team sports, and track and field events. Prior to the deployment of a comprehensive strength and conditioning program, strength and conditioning professionals should conduct a needs analysis that accounts for each sport’s technical, tactical, and logistical nuances to determine the program design principles of frequency, intensity, time, and type. 

About the author

Joseph Giandonato, PhD, MBA, CSCS is an Assistant Professor of Exercise Science at an institution in the Northeastern US. Previously, Giandonato supported an award-winning employee wellness program at a major university in the Mid-Atlantic US while serving as an adjunct faculty member at several colleges and universities where he taught exercise physiology, statistics, and research methods. Giandonato previously served as a strength and conditioning coach and has extensive experience working with professional, collegiate, and high school athletes. His research interests include ergogenic aids, concurrent training, and exploring health behaviors of non-traditional undergraduate students.