Question

what would be the simplest way to summarize this in 150 words ?

Maintaining muscle mass and function during rehabilitation from anterior cruciate ligament (ACL) injury is complicated by the challenge of accurately prescribing daily energy intakes aligned to energy expenditure. Accordingly, we present a 38-week case study characterizing whole body and regional rates of muscle atrophy and hypertrophy (as inferred by assessments of fat free mass from DXA) in a professional male soccer player from the English Premier League. Additionally, in week 6 we also quantified energy intake (via the remote food photographic method) and energy expenditure using the doubly labeled water method. Mean daily energy intake (CHO: 1.9-3.2, Protein: 1.7-3.3 and Fat: 1.4-2.7 g.kg-1) and energy expenditure was 2765 ± 474 and 3178 kcal.d-1 respectively. In accordance with an apparent energy deficit, total body mass decreased by 1.9 kg during week 1-6 where FFM loss in the injured and non-injured limb was 0.9 and 0.6 kg, respectively, yet, trunk FFM increased by 0.7 kg. In weeks 7-28, the athlete was advised to increased daily CHO intake (4-6 g.kg-1) to facilitate an increased daily energy intake. Throughout this period, total body mass increased by 3.6 kg (attributable to a 2.9 and 0.7 kg increase in fat-free and fat mass, respectively). Our data suggest it may be advantageous to avoid excessive reductions in energy intake during the initial 6-8 weeks post-ACL surgery so as to limit muscle atrophy.

Maintaining muscle mass and function during rehabilitation from ACL injury is complicated by the challenge of accurately prescribing daily energy intakes aligned to energy expenditure. Indeed, in a previous case-study study by our group (Milsom et al. 2014), we observed a whole body FFM loss of 5.8 kg (3.8 kg of which was from the trunk) in the initial 8 weeks after surgery. Accordingly, the specific aim of the present case-study was to quantify energy expenditure (via the DLW method) during a training micro-cycle where the athlete may be particularly susceptible to muscle atrophy i.e in the initial 6-8 weeks after surgery. Additionally, we also quantified body composition changes (via DXA) during the 38-week rehabilitation period.

In contrast to our previous study, the athlete studied here was not immobilized at any time-point during the rehabilitation period. Given the large atrophy observed previously (where daily energy intake was <2000 kcal.d-1 and no form of upper body resistance training was performed during the initial 8 weeks after surgery), the initial 6-week intervention detailed here focused on achieving higher daily energy intakes (i.e. 2500-3000 kcal.d-1) as well as incorporating 3 upper body resistance training sessions per week. In accordance with no specific immobilization phase, the athlete was also able to complete 5 lower body strength- training sessions per week. As such, the combination of increased daily energy intake and higher absolute loading of both the trunk and lower limbs was apparently successful in reducing rates of whole body muscle atrophy (-0.1 versus -0.73 kg per week), injured limb atrophy (- 0.15 versus -0.18 kg per week) and trunk muscle atrophy (+0.1 versus -0.48 kg per week) when compared to the athlete studied by Milsom et al. (2014). When taken together, these data suggest it may be advantageous to avoid excessive reductions in energy intake as well as maintaining a contractile stimulus to the non-injured muscle groups.

In an attempt to better understand the energy requirements during the early phase of

rehabilitation, we also quantified energy expenditure using the DLW method. In week 6, we

observed a mean daily energy expenditure of 3178 kcal.d-1 and a mean daily energy intake of

-1
2765 ± 474 kcal.d . Examination of daily energy intake data also demonstrated that the athlete

was likely in energy deficit on 6 of the 7 days of this specific micro-cycle. In relation to the specific player studied here and the daily loading patterns, our data therefore suggest mean daily energy intakes of approximately 3000-3500 kcal.d-1 may have been required to maintain energy balance during the early stages of rehabilitation. We acknowledge, however, that additional assessments of energy expenditure and intake during week 1-5 would also have been beneficial so as to provide further inferences on daily energy balance.

It is noteworthy that the energy expenditure observed here was only 300 kcal.d-1 less than that observed in outfield players from the same team (as studied during a 2 game per week microcycle; Anderson et al., 2017a) but yet, 300 kcal.d-1 more than a goalkeeper from the same team (Anderson et al., 2018). Despite the reduced absolute intensity of training when compared with outfield players, it is therefore apparent that the increased duration and frequency of daily activities typically completed during rehabilitation (e.g the athlete performed rehabilitation activities in both the morning and afternoon) may manifest as a total daily energy requirement that is comparable to outfield players. Accordingly, from week 6 onwards the player was advised to increase daily energy intake (via increasing daily CHO intake to 4-6 g.kg) in an attempt to promote muscle hypertrophy. In this regard, the presentation of body composition data in Figure 1 and 2 suggest that the increased daily energy intake in accordance with maintaining high daily protein intake and increased whole body loading (see Table 1) was successful in inducing muscle hypertrophy in the trunk and both the injured and non-injured limbs. It is acknowledged that additional assessments of energy expenditure could also be made at various stages of the rehabilitation phase so as to further aid accurate energy and macronutrient prescriptions.

As with all case-study accounts, the limitations are that only one player was studied whilst under a specific program that was underpinned by the philosophy of the performance and medical department within the club of investigation. Whilst this player was subjected to a

similar rehabilitation program and staffing base as the player studied by Milsom et al. (2014), there is a definitive need to also study the energy requirements of additional players from different teams during rehabilitation from long-term injuries. Such a collaborative effort will help to optimize nutritional interventions for injured athletes.

In summary, our data suggest that daily energy requirements during the initial 6 weeks of rehabilitation may be comparable to that of outfield players, likely due to the increased duration of daily activities and the energetic cost of repairing injured tissues. It may therefore be advantageous to avoid excessive reductions in energy intake during the early rehabilitation period, begin loading of the injured limb as soon as possible and incorporate training activities that maintain a contractile stimulus to the non-injured muscle groups. Whilst we acknowledge that any nutritional strategy should be tailored to the specific athletic situation, it is hoped that the publication of these data will prompt further reflection of the loading patterns and nutritional strategies that can help achieve successful rehabilitation from long term injury.

Answer 1

Rehabilitation after ACL injury a summary

Maintaining muscle mass and function during rehabilitation from anterior cruciate ligament (ACL) injury is complicated.According to english premier League study Mean daily energy intake (CHO: 1.9-3.2, Protein: 1.7-3.3 and Fat: 1.4-2.7 g.kg-1) and energy expenditure was 2765 ± 474 and 3178 kcal.d-1 respectively. In accordance with an apparent energy deficit, total body mass decreased by 1.9 kg during week 1-6 where FFM loss in the injured and non-injured limb was 0.9 and 0.6 kg, respectively, yet, trunk FFM increased by 0.7 kg. In weeks 7-28, the athlete was advised to increased daily CHO intake (4-6 g.kg-1) to facilitate an increased daily energy intake. Throughout this period, total body mass increased by 3.6 kg.It will be advantageous to avoid excessive reductions in energy intake during the initial 6-8 weeks post-ACL surgery so as to limit muscle atrophy. Here a whole body FFM loss of 5.8 kg was obseeved in the initial 8 weeks after surgery. Accordingly, the specific aim of the second case-study was to quantify energy expenditure (via the DLW method) during a training micro-cycle where the athlete may be particularly susceptible to muscle atrophy i.e in the initial 6-8 weeks after surgery. In this study by Milosom et al 2014, highlights that combination of increased daily energy intake and higher absolute loading of both the trunk and lower limbs was apparently successful in reducing rates of whole body muscle atrophy, injured limb atrophy and trunk muscle atrophy.When taken together, these data suggest it may be advantageous to avoid excessive reductions in energy intake as well as maintaining a contractile stimulus to the non-injured muscle groups.It is noteworthy that the energy expenditure observed here was only 300 kcal.

Daily energy requirements during the initial 6 weeks of rehabilitation may be comparable to that of outfield players, likely due to the increased duration of daily activities and the energetic cost of repairing injured tissues. It may therefore be advantageous to avoid excessive reductions in energy intake during the early rehabilitation period, begin loading of the injured limb as soon as possible and incorporate training activities that maintain a contractile stimulus to the non-injured muscle groups.