European Journal of Applied Physiology (2021) 121:3551–3559
Contralateral strength training attenuates muscle performance
loss followinganterior cruciate ligament (ACL) reconstruction:
ClaireMinshull1,2 · PeterGallacher1· SimonRoberts1· AndrewBarnett1· JanHermanKuiper1,3· AndreaBailey1
Received: 26 April 2021 / Accepted: 11 September 2021 / Published online: 20 September 2021
© The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2021
Purpose To investigate the eﬀects of cross-education (CE) exercise on strength and performance at 10 and 24weeks post
anterior cruciate ligament (ACL) surgery.
Methods Design: randomised controlled trial. N = 44 ACL-reconstruction patients, randomly-allocated into: CE: strength
training of the non-operative limb, or CON: sham exercise of upper limb stretching. Each patient underwent standardised
ACL rehabilitation, plus 8weeks of thrice weekly CE or CON, commencing at 2weeks post surgery. The primary outcome
was quadriceps peak force (QPF) of the ACL-reconstructed limb at 10weeks post surgery. Secondary measures were ham-
strings peak force (HPF), rate of force development (RFD) and International Knee Documentation Committee score (IKDC)
at 10 and 24weeks; QPF and hop for distance (HOP) at 24weeks post surgery.
Results CE signiﬁcantly attenuated the decline in QPF of the ACL-reconstructed limb at 10weeks compared to CON (16.6%
decrease vs. 32.0%, respectively); that advantage was not retained at 24weeks. A training eﬀect was observed in the trained
limb for HPF and QPF, which was retained at 24weeks. No signiﬁcant diﬀerences were observed for IKDC, HOP, RFD,
or HPF of the reconstructed limb. Inter-limb symmetry (ILS) ranged from 0.78 to 0.89 and was not signiﬁcantly diﬀerent
Conclusion High-intensity CE strength training attenuated the post-operative decline in QPF and should be considered in
early-phase ACL rehabilitation. ILS data showed good symmetry, but it masked signiﬁcantly inferior performance between
groups and should be used with caution.
Trial registration number NCT02722876.
Keywords Cross-education· Cross-transfer· Rehabilitation· Strength training
ACL Anterior cruciate ligament
QPF Quadriceps peak force
HPF Hamstrings peak force
RFD Rate of force development
ILS Inter-limb symmetry
IKDC International knee documentation
Anterior cruciate ligament (ACL) injury is a common and
debilitating injury (Ardern etal. 2011; Sanders etal. 2016)
and without intervention often prevents return to play. Surgi-
cal reconstruction to restore mechanical rotational instability
(Krause etal. 2018) is the preferred treatment option, where
patients have ongoing symptoms of instability despite con-
servative treatment (Schmitt etal. 2012).
ACL reconstruction (ACLR) often results in signiﬁcant
and prolonged functional impairments, in particular asym-
metry of quadriceps strength (Gokeler etal. 2014; Kuenze
Communicated by Toshio Moritani.
* Claire Minshull
1 Research Department, RJAH Orthopaedic Hospital NHS
Foundation Trust, OswestrySY107AG, UK
2 Get Back To Sport Ltd, Nottingham, UK
3 School ofPharmacy andBioengineering, Keele University,
Keele, StaﬀordshireST55BG, UK