This is an excerpt from Complete Conditioning for Soccer by Ryan Alexander.
The external defender, also called a fullback, has several modifiable roles based on the playing style of the team. One consistent aspect of the physical demands of a fullback is the significant amount of total distance and high-intensity work completed during competition. Theoretically, this is due to the greater area of the playing field the external defender typically covers (figure 1.4).
Figure 1.4 The external defender's typical work area.
Since the turn of the century when academics started to separate the external defender from the central defender position, most scholars have agreed that the external defender is comparable to the central midfielder as one of the most physically demanding positions on the field. The average total distance covered for external defenders from table 1.1 is 10,642 meters or 6.61 miles, compared to 9,871 meters or 6.14 miles for central defenders. The most difficult field position is ultimately going to be based on the tactical implementation of the technical staff, and the fullback position is one that can be highly influenced by formation and tactics.
Overall, the total distance covered by the external defenders has plateaued around 10,000 to 11,000 meters (6.2-6.8 miles; table 1.1). High-intensity work (work completed above 5.5 m/s) is approximately 1,000 meters (1,094 yd; depending on the player level) with a wide standard deviation for male fullbacks (Rampinini et al. 2007; Bradley et al. 2009) and approximately 650 meters (711 yd) for female fullbacks (Bradley et al. 2013). Opposite from the central defender, the fullback typically does not have the same player congestion in the wide areas of the field and does typically manage their positioning based on the sideline, which results in playing within a 180-degree arc. This is important for two reasons:
- When considering conditioning prescriptions, changes of direction within tight areas isn't as important for external players. A greater emphasis on longer runs at higher velocities is more appropriate to meet the typical demands of this position during competition.
- Because of the lower player congestion, there is a lower likelihood of explosive movements or movements from a standstill into a high-intensity action. Another way of interpreting this is external players have a lead-in or run-up into high-intensity actions. When considering elements of conditioning exercises, this is a key factor that can inspire pertinent individualization during the early weeks of the preseason.
The external defender also presents a significantly different activity profile from other positions when considering time between high-intensity actions. In a study analyzing the top men's league in France, researchers found the external defender had the shortest average recovery time between high-intensity bouts (115.8 seconds ± 18.6; Carling, Le Gall, and Dupont 2012). This heightens the importance of work-to-rest ratios and overloading the recovery processes of the body for this position during the early stages of the preseason.
With respect to anthropometrics, the external defender is typically smaller and lighter than the central defender and goalkeeper, and they are comparable to the midfielder and forward positions (Boone et al. 2012). Lighter and smaller players, in general, will have a greater ability to cover more distance during a match because of the increased efficiency in the body's ability to produce force at both high and low intensities. Anthropometrics can be an easy starting point for consideration for specific positions. Considering the typical fullback covers close to 6.5 miles and runs nearly three-quarters of a mile in high-intensity zones, in general, I recommend lighter players over ones of greater mass in the external positions because of the demand on total work output.